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serverStatus (database command)

Definition

serverStatus: The serverStatus command returns a document that provides an overview of the database's state. Monitoring applications can run this command at a regular interval to collect statistics about the instance.

Compatibility

This command is available in deployments hosted in the following environments:

MongoDB Atlas: The fully managed service for MongoDB deployments in the cloud

Note

This command is supported in all MongoDB Atlas clusters. For information on Atlas support for all commands, see Unsupported Commands.

MongoDB Enterprise: The subscription-based, self-managed version of MongoDB
MongoDB Community: The source-available, free-to-use, and self-managed version of MongoDB

Syntax

The command has the following syntax:

db.runCommand(
   {
     serverStatus: 1
   }
)

The value (i.e. 1 above) does not affect the operation of the command. The db.serverStatus() command returns a large amount of data. To return a specific object or field from the output append the object or field name to the command.

For example:

db.runCommand({ serverStatus: 1}).metrics
db.runCommand({ serverStatus: 1}).metrics.commands
db.runCommand({ serverStatus: 1}).metrics.commands.update

mongosh provides the db.serverStatus() wrapper for the serverStatus command.

Tip

Much of the output of serverStatus is also displayed dynamically by mongostat. See the mongostat command for more information.

Behavior

By default, serverStatus excludes in its output:

some content in the repl document.
mirroredReads document.

To include fields that are excluded by default, specify the top-level field and set it to 1 in the command. To exclude fields that are included by default, specify the field and set to 0. You can specify either top-level or embedded fields.

For example, the following operation excludes the repl, metrics and locks information in the output.

db.runCommand( { serverStatus: 1, repl: 0, metrics: 0, locks: 0 } )

For example, the following operation excludes the embedded histogram field in the output.

db.runCommand( { serverStatus: 1, metrics: { query: { multiPlanner: { histograms: false } } } } )

The following example includes all repl information in the output:

db.runCommand( { serverStatus: 1,  repl: 1 } )

Initialization

The statistics reported by serverStatus are reset when the mongod server is restarted.

This command will always return a value, even on a fresh database. The related command db.serverStatus() does not always return a value unless a counter has started to increment for a particular metric.

After you run an update query, db.serverStatus() and db.runCommand({ serverStatus: 1}) both return the same values.

{
   arrayFilters : Long("0"),
   failed : Long("0"),
   pipeline : Long("0"),
   total : Long("1")
}

Include `mirroredReads`

By default, the mirroredReads information is not included in the output. To return mirroredReads information, you must explicitly specify the inclusion:

db.runCommand( { serverStatus: 1, mirroredReads: 1 } )

Output

Note

The output fields vary depending on the version of MongoDB, underlying operating system platform, the storage engine, and the kind of node, including mongos, mongod or replica set member.

For the serverStatus output specific to the version of your MongoDB, refer to the appropriate version of the MongoDB Manual.

asserts

asserts: {
   regular: <num>,
   warning: <num>,
   msg: <num>,
   user: <num>,
   rollovers: <num>
},

asserts: A document that reports on the number of assertions raised since the MongoDB process started. Assertions are internal checks for errors that occur while the database is operating and can help diagnose issues with the MongoDB server. Non-zero asserts values indicate assertion errors, which are uncommon and not an immediate cause for concern. Errors that generate asserts can be recorded in the log file or returned directly to a client application for more information.

asserts.regular: The number of regular assertions raised since the MongoDB process started. Examine the MongoDB log for more information.

asserts.warning: This field always returns zero 0.

asserts.msg: The number of message assertions raised since the MongoDB process started. Examine the log file for more information about these messages.

asserts.user: The number of "user asserts" that have occurred since the last time the MongoDB process started. These are errors that user may generate, such as out of disk space or duplicate key. You can prevent these assertions by fixing a problem with your application or deployment. Server logs may have limited information about "user asserts." To learn more information about the source of "user asserts," check the application logs for application errors.

asserts.rollovers: The number of times that the assert counters have rolled over since the last time the MongoDB process started. The counters will roll over to zero after 2 ³⁰ assertions. Use this value to provide context to the other values in the asserts data structure.

bucketCatalog

bucketCatalog: {
    numBuckets: <num>,
    numOpenBuckets: <num>,
    numIdleBuckets: <num>,
    memoryUsage: <num>,
    numBucketInserts: <num>,
    numBucketUpdates: <num>,
    numBucketsOpenedDueToMetadata: <num>,
    numBucketsClosedDueToCount: <num>,
    numBucketsClosedDueToSchemaChange: <num>,
    numBucketsClosedDueToSize: <num>,
    numBucketsClosedDueToTimeForward: <num>,
    numBucketsClosedDueToTimeBackward: <num>,
    numBucketsClosedDueToMemoryThreshold: <num>,
    numCommits: <num>,
    numMeasurementsGroupCommitted: <num>,
    numWaits: <num>,
    numMeasurementsCommitted: <num>,
    avgNumMeasurementsPerCommit: <num>,
    numBucketsClosedDueToReopening: <num>,
    numBucketsArchivedDueToMemoryThreshold: <num>,
    numBucketsArchivedDueToTimeBackward: <num>,
    numBucketsReopened: <num>,
    numBucketsKeptOpenDueToLargeMeasurements: <num>,
    numBucketsClosedDueToCachePressure: <num>,
    numBucketsFrozen: <num>,
    numCompressedBucketsConvertedToUnsorted: <num>,
    numBucketsFetched: <num>,
    numBucketsQueried: <num>,
    numBucketFetchesFailed: <num>,
    numBucketQueriesFailed: <num>,
    numBucketReopeningsFailed: <num>,
    numDuplicateBucketsReopened: <num>,
    stateManagement: {
       bucketsManaged: <num>,
       currentEra: <num>,
       erasWithRemainingBuckets: <num>,
       trackedClearOperations: <num>
    }
 }

New in version 5.0.

A document that reports metrics related to the internal storage of time series collections.

The bucketCatalog returns the following metrics:

Metric	Description
`numBuckets`	The total number of tracked buckets. Expected to be equal to the sum of `numOpenBuckets` and `numArchivedBuckets`.
`numOpenBuckets`	The number of tracked buckets with a full representation stored in-cache, ready to receive new documents.
`numIdleBuckets`	The number of buckets that are open and currently without an uncommitted document insertion pending. A subset of numOpenBuckets.
`numArchivedBuckets`	The number of tracked buckets with a minimal representation stored in-cache that can be efficiently reopened to receive new documents.
`memoryUsage`	The number of bytes used by internal bucketing data structures.
`numBucketInserts`	The number of new buckets created.
`numBucketUpdates`	The number times an existing bucket was updated to include additional documents.
`numBucketsOpenedDueToMetadata`	The number of buckets opened because a document arrived with a `metaField` value that didn't match any currently open buckets.
`numBucketsClosedDueToCount`	The number of buckets closed due to reaching their document count limit.
`numBucketsClosedDueToSchemaChange`	The number of buckets closed because the schema of an incoming document was incompatible with that of the documents in the open bucket.
`numBucketsClosedDueToSize`	The number of buckets closed because an incoming document would make the bucket exceed its size limit.
`numBucketsClosedDueToTimeForward`	The number of buckets closed because a document arrived with a `timeField` value after the maximum time of all currently open buckets for that `metaField` value.
`numBucketsClosedDueToTimeBackward`	The number of buckets closed because a document arrived with a `timeField` value before the minimum time of all currently open buckets for that `metaField` value.
`numBucketsClosedDueToMemoryThreshold`	The number of buckets closed because the set of active buckets didn't fit within the allowed bucket catalog cache size.
`numCommits`	The number of bucket-level commits to the time series collection.
`numMeasurementsGroupCommitted`	The number of commits that included measurements from concurrent insert commands.
`numWaits`	The number of times an operation waited on another thread to either reopen a bucket or finish a group commit.
`numMeasurementsCommitted`	The number of documents committed to the time series collection.
`avgNumMeasurementsPerCommit`	The average number of documents per commit.
`numBucketsClosedDueToReopening`	The number of buckets closed because a suitable bucket was re-opened instead.
`numBucketsArchivedDueToMemoryThreshold`	The number of buckets archived because the set of active buckets didn't fit within the allowed bucket catalog cache size.
`numBucketsArchivedDueToTimeBackward`	The number of buckets archived because a document arrived with a `timeField` value before the minimum time of all currently open buckets for that `metaField` value.
`numBucketsReopened`	The number of buckets re-opened because a document arrived that didn't match any open buckets, but did match an existing non-full bucket.
`numBucketsKeptOpenDueToLargeMeasurements`	The number of buckets that would have been closed due size, but were kept open due to not containing a minimum number of documents required to achieve reasonable compression.
`numBucketsClosedDueToCachePressure`	The number of buckets closed because their size exceeds the bucket catalog's dynamic bucket size limit derived from available storage engine cache size and `numBuckets`. This limit is distinct from the maximum bucket size limit.
`numBucketsFrozen`	The number of frozen buckets. Buckets are frozen if attempting to compress the bucket would corrupt its contents.
`numCompressedBucketsConvertedToUnsorted`	The number of compressed buckets that contain documents not sorted by their respective `timeField` values.
`numBucketsFetched`	The number of archived buckets fetched to check if they were suitable for re-opening.
`numBucketsQueried`	The total number of buckets queried to see if they could hold an incoming document.
`numBucketFetchesFailed`	The number of archived buckets fetched that were not suitable for re-opening.
`numBucketQueriesFailed`	The number of queries for a suitable open bucket that failed due to lack of candidate availability.
`numBucketReopeningsFailed`	The number of attempted bucket reopenings that failed due to reasons including conflicts with concurrent operations, malformed buckets, and more.
`numDuplicateBucketsReopened`	The number of re-opened buckets that are duplicates of currently open buckets.
`stateManagement`	A document that tracks bucket catalog state information.
`stateManagement.bucketsManaged`	The total number of buckets that are being tracked for conflict management. This includes open buckets in the bucket catalog as well as any buckets that are being directly written to, including by update and delete commands.
`stateManagement.currentEra`	The current era of the bucket catalog. The bucket catalog starts at era 0 and increments when a bucket is cleared. Attempting to insert into a bucket will either cause it to be removed if it was cleared, or update it to the current era.
`stateManagement.erasWithRemainingBuckets`	The number of eras with tracked buckets.
`stateManagement.trackedClearOperations`	The number of times the a set of buckets has been cleared, but the removal of those buckets was deferred. This can happen due to events such as dropping a collection, moving a chunk in a sharded collection, or an election.

You can also use the $collStats aggregation pipeline stage to find time series metrics. To learn more, see storageStats Output on Time Series Collections.

catalogStats

New in version 5.1.

catalogStats: {
   collections: <num>,
   capped: <num>,
   views: <num>,
   timeseries: <num>,
   internalCollections: <num>,
   internalViews: <num>,
   systemProfile: <num>
}

catalogStats: A document that reports statistics on collection usage via collection counts.

catalogStats.collections: The total number of user collections (not including system collections).

catalogStats.capped: The total number of capped user collections.

catalogStats.views: The total number of user views.

catalogStats.timeseries: The total number of time series collections.

catalogStats.internalCollections: The total number of system collections (collections on the config, admin, or local databases).

catalogStats.internalViews: The total number of views of system collections (collections on the config, admin, or local databases).

catalogStats.systemProfile: The total number of profile collections on all databases.

changeStreamPreImages

New in version 5.0.

changeStreamPreImages : {
   purgingJob : {
      totalPass : <num>,
      docsDeleted : <num>,
      bytesDeleted : <num>,
      scannedCollections : <num>,
      scannedInternalCollections : <num>,
      maxTimestampEligibleForTruncate : <timestamp>,
      maxStartWallTimeMillis : <num>,
      timeElapsedMillis : <num>,
   },
   expireAfterSeconds : <num>
}

A document that reports metrics related to change stream pre-images.

changeStreamPreImages.purgingJob

New in version 7.1.

A document that reports metrics related to the purging jobs for change stream pre-images. Purging jobs are background processes that the system uses to remove pre-images asynchronously.

The changeStreamPreImages.purgingJob field returns the following metrics:

Metric	Description
`totalPass`	Total number of deletion passes completed by the purging job.
`docsDeleted`	Cumulative number of pre-image documents deleted by the purging job.
`bytesDeleted`	Cumulative size in bytes of all deleted documents from all pre-image collections by the purging job.
`scannedCollections`	Cumulative number of pre-image collections scanned by the purging job. In single-tenant environments, this number is the same as `totalPass` since each tenant has one pre-image collection.
`scannedInternalCollections`	Cumulative number of internal pre-image collections scanned by the purging job. Internal collections are the collections within the pre-image collections stored in `config.system.preimages`.
`maxTimestampEligibleForTruncate`	Most recent timestamp up to which old pre-images can be truncated to reduce storage space. Pre-images older than `maxTimestampEligibleForTruncate` can be truncated. New in version 8.1.
`maxStartWallTimeMillis`	Maximum wall time in milliseconds from the first document of each pre-image collection.
`timeElapsedMillis`	Cumulative time in milliseconds of all deletion passes by the purging job.

changeStreamPreImages.expireAfterSeconds: New in version 7.1.
Amount of time in seconds that MongoDB retains pre-images. If expireAfterSeconds is not defined, this metric does not appear in the serverStatus output.

connections

connections : {
   current : <num>,
   available : <num>,
   totalCreated : <num>,
   rejected : <num>,  // Added in MongoDB 6.3
   active : <num>,
   threaded : <num>,
   exhaustIsMaster : <num>,
   exhaustHello : <num>,
   awaitingTopologyChanges : <num>,
   loadBalanced : <num>,
   queuedForEstablishment : <num>, // Added in MongoDB 8.2 *(also available in 8.1.1, 8.0.12, and 7.0.23)*
   establishmentRateLimit : { // Added in MongoDB 8.2 *(also available in 8.1.1, 8.0.12, and 7.0.23)*
      rejected: <num>,
      exempted: <num>,
      interruptedDueToClientDisconnect: <num>
   }
}

connections: A document that reports on the status of the connections. Use these values to assess the current load and capacity requirements of the server.

connections.current

The number of incoming connections from clients to the database server. This number includes the current shell session. Consider the value of connections.available to add more context to this datum.

The value will include all incoming connections including any shell connections or connections from other servers, such as replica set members or mongos instances.

connections.available: The number of unused incoming connections available. Consider this value in combination with the value of connections.current to understand the connection load on the database, and the UNIX ulimit Settings for Self-Managed Deployments document for more information about system thresholds on available connections.

connections.totalCreated: Count of all incoming connections created to the server. This number includes connections that have since closed.

connections.rejected: New in version 6.3.
The number of incoming connections the server rejected because the server doesn't have the capacity to accept additional connections or the net.maxIncomingConnections setting is reached.

connections.queuedForEstablishment: New in version 8.2: (also available in 8.1.1, 8.0.12, and 7.0.23)
The number of incoming connections currently queued and waiting for establishment. This metric is relevant when connection establishment rate limiting is enabled using the ingressConnectionEstablishmentRateLimiterEnabled parameter.

connections.establishmentRateLimit: New in version 8.2: (also available in 8.1.1, 8.0.12, and 7.0.23)
A document that contains metrics related to the ingress connection establishment rate limiter. These metrics provide insights into how the rate limiter handles connection requests when ingressConnectionEstablishmentRateLimiterEnabled is set to true. For more information on rate limiting, see Configure the Ingress Connection Establishment Rate Limiter.

connections.establishmentRateLimit.rejected: New in version 8.2: (also available in 8.1.1, 8.0.12, and 7.0.23)
The number of incoming connections the server rejects due to connection establishment rate limiting. This metric shows how many connection attempts the server rejected rejected because they exceeded the rate limits set by the ingress connection establishment rate limiter parameters.

connections.establishmentRateLimit.exempted: New in version 8.2: (also available in 8.1.1, 8.0.12, and 7.0.23)
The number of incoming connections that bypassed the rate limiter because they originated from IP addresses or CIDR ranges specified in the ingressConnectionEstablishmentRateLimiterBypass parameter. The server does note rate limit these connections and establishes them immediately, regardless of current queue size or rate limits.

connections.establishmentRateLimit.interruptedDueToClientDisconnect: New in version 8.2: (also available in 8.1.1, 8.0.12, and 7.0.23)
The number of incoming connections that were interrupted while waiting in the establishment queue because the client disconnected before establishment could complete. A high value for this metric sometimes indicates that the client's connectTimeoutMS setting is too short relative to the queue wait time, which is affected by ingressConnectionEstablishmentMaxQueueDepth and ingressConnectionEstablishmentRatePerSec. If this value is high, consider adjusting these parameters using the following formula: maxQueueDepth < (establishmentRatePerSec / 1000) * (connectTimeoutMs - avgEstablishmentTimeMs).

connections.active: The number of active client connections to the server. Active client connections refers to client connections that currently have operations in progress.

connections.threaded: The number of incoming connections from clients that are assigned to threads that service client requests.
New in version 5.0.

connections.exhaustIsMaster: The number of connections whose last request was an isMaster request with exhaustAllowed.
Note
If you are running MongoDB 5.0 or later, do not use the isMaster command. Instead, use hello.

connections.exhaustHello: The number of connections whose last request was a hello request with exhaustAllowed.
New in version 5.0.

connections.awaitingTopologyChanges: The number of clients currently waiting in a hello or isMaster request for a topology change.
Note
If you are running MongoDB 5.0 or later, do not use the isMaster command. Instead, use hello.

connections.loadBalanced: New in version 5.3.
The current number of incoming connections received through the load balancer.

defaultRWConcern

The defaultRWConcern section provides information on the local copy of the global default read or write concern settings. The data may be stale or out of date. See getDefaultRWConcern for more information.

defaultRWConcern : {
  defaultReadConcern : {
    level : <string>
  },
  defaultWriteConcern : {
    w : <string> | <int>,
    wtimeout : <int>,
    j : <bool>
  },
  defaultWriteConcernSource: <string>,
  defaultReadConcernSource: <string>,
  updateOpTime : Timestamp,
  updateWallClockTime : Date,
  localUpdateWallClockTime : Date
}

defaultRWConcern: The last known global default read or write concern settings.

defaultRWConcern.defaultReadConcern

The last known global default read concern setting.

If serverStatus does not return this field, the global default read concern has either not been set or has not yet propagated to the instance.

defaultRWConcern.defaultReadConcern.level

The last known global default read concern level setting.

If serverStatus does not return this field, the global default for this setting has either not been set or has not yet propagated to the instance.

defaultRWConcern.defaultWriteConcern

The last known global default write concern setting.

If serverStatus does not return this field, the global default write concern has either not been set or has not yet propagated to the instance.

defaultRWConcern.defaultWriteConcern.w

The last known global default w setting.

If serverStatus does not return this field, the global default for this setting has either not been set or has not yet propagated to the instance.

defaultRWConcern.defaultWriteConcern.wtimeout

The last known global default wtimeout setting.

If serverStatus does not return this field, the global default for this setting has either not been set or has not yet propagated to the instance.

defaultRWConcern.defaultWriteConcernSource: The source of the default write concern. By default, the value is "implicit". Once you set the default write concern with setDefaultRWConcern, the value becomes "global".
New in version 5.0.

defaultRWConcern.defaultReadConcernSource: The source of the default read concern. By default, the value is "implicit". Once you set the default read concern with setDefaultRWConcern, the value becomes "global".
New in version 5.0.

defaultRWConcern.updateOpTime: The timestamp when the instance last updated its copy of any global read or write concern settings. If the defaultRWConcern.defaultReadConcern and defaultRWConcern.defaultWriteConcern fields are absent, this field indicates the timestamp when the defaults were last unset.

defaultRWConcern.updateWallClockTime: The wall clock time when the instance last updated its copy of any global read or write concern settings. If the defaultRWConcern.defaultReadConcern and defaultRWConcern.defaultWriteConcern fields are absent, this field indicates the time when the defaults were last unset.

defaultRWConcern.localUpdateWallClockTime: The local system wall clock time when the instance last updated its copy of any global read or write concern setting. If this field is the only field under defaultRWConcern, the instance has never had knowledge of a global default read or write concern setting.

electionMetrics

The electionMetrics section provides information on elections called by this mongod instance in a bid to become the primary:

electionMetrics : {
   stepUpCmd : {
      called : Long("<num>"),
      successful : Long("<num>")
   },
   priorityTakeover : {
      called : Long("<num>"),
      successful : Long("<num>")
   },
   catchUpTakeover : {
      called : Long("<num>"),
      successful : Long("<num>")
   },
   electionTimeout : {
      called : Long("<num>"),
      successful : Long("<num>")
   },
   freezeTimeout : {
      called : Long("<num>"),
      successful : Long("<num>")
   },
   numStepDownsCausedByHigherTerm : Long("<num>"),
   numCatchUps : Long("<num>"),
   numCatchUpsSucceeded : Long("<num>"),
   numCatchUpsAlreadyCaughtUp : Long("<num>"),
   numCatchUpsSkipped : Long("<num>"),
   numCatchUpsTimedOut : Long("<num>"),
   numCatchUpsFailedWithError : Long("<num>"),
   numCatchUpsFailedWithNewTerm : Long("<num>"),
   numCatchUpsFailedWithReplSetAbortPrimaryCatchUpCmd : Long("<num>"),
   averageCatchUpOps : <double>
}

electionMetrics.stepUpCmd

Metrics on elections that were called by the mongod instance as part of an election handoff when the primary stepped down.

The stepUpCmd includes both the number of elections called and the number of elections that succeeded.

electionMetrics.priorityTakeover

Metrics on elections that were called by the mongod instance because its priority is higher than the primary's.

The electionMetrics.priorityTakeover includes both the number of elections called and the number of elections that succeeded.

electionMetrics.catchUpTakeover

Metrics on elections called by the mongod instance because it is more current than the primary.

The catchUpTakeover includes both the number of elections called and the number of elections that succeeded.

Tip

settings.catchUpTakeoverDelayMillis

electionMetrics.electionTimeout

Metrics on elections called by the mongod instance because it has not been able to reach the primary within settings.electionTimeoutMillis.

The electionTimeout includes both the number of elections called and the number of elections that succeeded.

Tip

settings.electionTimeoutMillis

electionMetrics.freezeTimeout

Metrics on elections called by the mongod instance after its freeze period (during which the member cannot seek an election) has expired.

The electionMetrics.freezeTimeout includes both the number of elections called and the number of elections that succeeded.

electionMetrics.numStepDownsCausedByHigherTerm: Number of times the mongod instance stepped down because it saw a higher term (specifically, other member(s) participated in additional elections).

electionMetrics.numCatchUps: Number of elections where the mongod instance as the newly-elected primary had to catch up to the highest known oplog entry.

electionMetrics.numCatchUpsSucceeded: Number of times the mongod instance as the newly-elected primary successfully caught up to the highest known oplog entry.

electionMetrics.numCatchUpsAlreadyCaughtUp: Number of times the mongod instance as the newly-elected primary concluded its catchup process because it was already caught up when elected.

electionMetrics.numCatchUpsSkipped: Number of times the mongod instance as the newly-elected primary skipped the catchup process.

electionMetrics.numCatchUpsTimedOut: Number of times the mongod instance as the newly-elected primary concluded its catchup process because of the settings.catchUpTimeoutMillis limit.

electionMetrics.numCatchUpsFailedWithError: Number of times the newly-elected primary's catchup process failed with an error.

electionMetrics.numCatchUpsFailedWithNewTerm: Number of times the newly-elected primary's catchup process concluded because another member(s) had a higher term (specifically, other member(s) participated in additional elections).

electionMetrics.numCatchUpsFailedWithReplSetAbortPrimaryCatchUpCmd: Number of times the newly-elected primary's catchup process concluded because the mongod received the replSetAbortPrimaryCatchUp command.

electionMetrics.averageCatchUpOps: Average number of operations applied during the newly-elected primary's catchup processes.

extra_info

extra_info : {
   note : 'fields vary by platform',
   page_faults : <num>
},

extra_info: A document that provides additional information about the underlying system.

extra_info.note: A string with the text 'fields vary by platform'

extra_info.page_faults

The total number of page faults. The extra_info.page_faults counter may increase dramatically during moments of poor performance and may correlate with limited memory environments and larger data sets. Limited and sporadic page faults do not necessarily indicate an issue.

Windows differentiates "hard" page faults involving disk I/O from "soft" page faults that only require moving pages in memory. MongoDB counts both hard and soft page faults in this statistic.

flowControl

flowControl : {
   enabled : <boolean>,
   targetRateLimit : <int>,
   timeAcquiringMicros : Long("<num>"),
   locksPerKiloOp : <double>,
   sustainerRate : <int>,
   isLagged : <boolean>,
   isLaggedCount : <int>,
   isLaggedTimeMicros : Long("<num>")
},

flowControl: A document that returns statistics on the Flow Control. With flow control enabled, as the majority commit point lag grows close to the flowControlTargetLagSeconds, writes on the primary must obtain tickets before taking locks. As such, the metrics returned are meaningful when run on the primary.

flowControl.enabled

A boolean that indicates whether Flow Control is enabled (true) or disabled (false).

globalLock

globalLock : {
   totalTime : Long("<num>"),
   currentQueue : {
      total : <num>,
      readers : <num>,
      writers : <num>
   },
   activeClients : {
      total : <num>,
      readers : <num>,
      writers : <num>
   }
},

globalLock

A document that reports on the database's lock state.

Generally, the locks document provides more detailed data on lock uses.

globalLock.totalTime: The time, in microseconds, since the database last started and created the globalLock. This is approximately equivalent to the total server uptime.

globalLock.currentQueue: A document that provides information concerning the number of operations queued because of a lock.

globalLock.currentQueue.total

The total number of operations queued waiting for the lock (i.e., the sum of globalLock.currentQueue.readers and globalLock.currentQueue.writers).

A consistently small queue, particularly of shorter operations, should cause no concern. The globalLock.activeClients readers and writers information provides context for this data.

globalLock.currentQueue.readers: The number of operations that are currently queued and waiting for the read lock. A consistently small read queue, particularly of shorter operations, should cause no concern.

globalLock.currentQueue.writers: The number of operations that are currently queued and waiting for the write lock. A consistently small write queue, particularly of shorter operations, is no cause for concern.

globalLock.activeClients

A document that provides information about the number of connected clients and the read and write operations performed by these clients.

Use this data to provide context for the globalLock.currentQueue data.

globalLock.activeClients.total: The total number of internal client connections to the database including system threads as well as queued readers and writers. This metric will be higher than the total of activeClients.readers and activeClients.writers due to the inclusion of system threads.

globalLock.activeClients.readers: The number of the active client connections performing read operations.

globalLock.activeClients.writers: The number of active client connections performing write operations.

indexBuilds

indexBuilds : {
   total : <num>,
   killedDueToInsufficientDiskSpace : <num>,
   failedDueToDataCorruption : <num>
},

indexBuilds: Provides metrics on index builds after the server last started.

indexBuilds.total: Total number of index builds.

indexBuilds.killedDueToInsufficientDiskSpace: Total number of index builds that were ended because of insufficient disk space. Starting in MongoDB 7.1, you can set the minimum amount of disk space required for building indexes using the indexBuildMinAvailableDiskSpaceMB parameter.
New in version 7.1.

indexBuilds.failedDueToDataCorruption: Total number of index builds that failed because of data corruption.
New in version 7.1.

indexBulkBuilder

indexBulkBuilder: {
   count: <long>,
   resumed: <long>,
   filesOpenedForExternalSort: <long>,
   filesClosedForExternalSort: <long>,
   spilledRanges: <long>,
   bytesSpilledUncompressed: <long>,
   bytesSpilled: <long>,
   numSorted: <long>,
   bytesSorted: <long>,
   memUsage: <long>
}

indexBulkBuilder: Provides metrics for index bulk builder operations. Use these metrics to diagnose index build issues with createIndexes, collection cloning during initial sync, index builds that resume after startup, and statistics on disk usage by the external sorter.

indexBuildBuilder.bytesSpilled: New in version 6.0.4.
The number of bytes written to disk by the external sorter.

indexBuilder.bytesSpilledUncompressed: New in version 6.0.4.
The number of bytes to be written to disk by the external sorter before compression.

indexBulkBuilder.count: The number of instances of the bulk builder created.

indexBulkBuilder.filesClosedForExternalSort: The number of times the external sorter closed a file handle to spill data to disk. Combine this value with filesOpenedForExternalSort to determine the number of open file handles in use by the external sorter.

indexBulkBuilder.filesOpenedForExternalSort: The number of times the external sorter opened a file handle to spill data to disk. Combine this value with filesClosedForExternalSort to determine the number of open file handles in use by the external sorter.

indexBulkBuilder.resumed: The number of times the bulk builder was created for a resumable index build.

indexBulkBuilder.spilledRanges: New in version 6.0.4.
The number of times the external sorter spilled to disk.

indexBulkBuilder.numSorted: New in version 6.3.
The total number of sorted documents.

indexBulkBuilder.bytesSorted: New in version 6.3.
The total number of bytes for sorted documents. For example, if a total of 10 documents were sorted and each document is 20 bytes, the total number of bytes sorted is 200.

indexBulkBuilder.memUsage: New in version 6.3.
The current bytes of memory allocated for building indexes.

indexStats

indexStats: {
   count: Long("<num>"),
   features: {
      '2d': { count: Long("<num>"), accesses: Long("<num>") },
      '2dsphere': { count: Long("<num>"), accesses: Long("<num>") },
      '2dsphere_bucket': { count: Long("<num>"), accesses: Long("<num>") },
      collation: { count: Long("<num>"), accesses: Long("<num>") },
      compound: { count: Long("<num>"), accesses: Long("<num>") },
      hashed: { count: Long("<num>"), accesses: Long("<num>") },
      id: { count: Long("<num>"), accesses: Long("<num>") },
      normal: { count: Long("<num>"), accesses: Long("<num>") },
      partial: { count: Long("<num>"), accesses: Long("<num>") },
      prepareUnique: { count: Long("<num>"), accesses: Long("<num>") }, // Added in 8.1 (and 8.0.4 and 7.0.14)
      single: { count: Long("<num>"), accesses: Long("<num>") },
      sparse: { count: Long("<num>"), accesses: Long("<num>") },
      text: { count: Long("<num>"), accesses: Long("<num>") },
      ttl: { count: Long("<num>"), accesses: Long("<num>") },
      unique: { count: Long("<num>"), accesses: Long("<num>") },
      wildcard: { count: Long("<num>"), accesses: Long("<num>") }
   }
}

indexStats: A document that reports statistics on all indexes on databases and collections in non-system namespaces only. indexStats does not report statistics on indexes in the admin, local, and config databases.
New in version 6.0.

indexStats.count: The total number of indexes.
New in version 6.0.

indexStats.features: A document that provides counters for each index type and the number of accesses on each index. Each index type under indexStats.features has a count field that counts the total number of indexes for that type, and an accesses field that counts the number of accesses on that index.
New in version 6.0.

Instance Information

host : <string>,
advisoryHostFQDNs : <array>,
version : <string>,
process : <'mongod'|'mongos'>,
service : <'router'|'shard'>,
pid : Long("<num>"),
uptime : <num>,
uptimeMillis : Long("<num>"),
uptimeEstimate : Long("<num>"),
localTime : ISODate("<Date>"),

host: The system's hostname. In Unix/Linux systems, this should be the same as the output of the hostname command.

advisoryHostFQDNs: An array of the system's fully qualified domain names (FQDNs).

version: The MongoDB version of the current MongoDB process.

process: The current MongoDB process. Possible values are: mongos or mongod.

service: The role of the current MongoDB process. Possible values are router or shard.
New in version 8.0.

pid: The process ID number.

uptime: The number of seconds that the current MongoDB process has been active.

uptimeMillis: The number of milliseconds that the current MongoDB process has been active.

uptimeEstimate: The uptime in seconds as calculated from MongoDB's internal course-grained time keeping system.

localTime: The ISODate representing the current time, according to the server, in UTC.

locks

locks : {
   <type> : {
         acquireCount : {
            <mode> : Long("<num>"),
            ...
         },
         acquireWaitCount : {
            <mode> : Long("<num>"),
            ...
         },
         timeAcquiringMicros : {
            <mode> : Long("<num>"),
            ...
         },
         deadlockCount : {
            <mode> : Long("<num>"),
            ...
         }
   },
   ...

locks

A document that reports for each lock <type>, data on lock <modes>.

The possible lock <types> are:

Lock Type	Description
`ParallelBatchWriterMode`	Represents a lock for parallel batch writer mode. In earlier versions, PBWM information was reported as part of the `Global` lock information.
`ReplicationStateTransition`	Represents lock taken for replica set member state transitions.
`Global`	Represents global lock.
`Database`	Represents database lock.
`Collection`	Represents collection lock.
`Mutex`	Represents mutex.
`Metadata`	Represents metadata lock.
`DDLDatabase`	Represents a DDL database lock. New in version 7.1.
`DDLCollection`	Represents a DDL collection lock. New in version 7.1.
`oplog`	Represents lock on the oplog.

The possible <modes> are:

Lock Mode	Description
`R`	Represents Shared (S) lock.
`W`	Represents Exclusive (X) lock.
`r`	Represents Intent Shared (IS) lock.
`w`	Represents Intent Exclusive (IX) lock.

All values are of the Long() type.

locks.<type>.acquireCount: Number of times the lock was acquired in the specified mode.

locks.<type>.acquireWaitCount: Number of times the locks.<type>.acquireCount lock acquisitions encountered waits because the locks were held in a conflicting mode.

locks.<type>.timeAcquiringMicros

Cumulative wait time in microseconds for the lock acquisitions.

locks.<type>.timeAcquiringMicros divided by locks.<type>.acquireWaitCount gives an approximate average wait time for the particular lock mode.

locks.<type>.deadlockCount: Number of times the lock acquisitions encountered deadlocks.

logicalSessionRecordCache

logicalSessionRecordCache : {
   activeSessionsCount : <num>,
   sessionsCollectionJobCount : <num>,
   lastSessionsCollectionJobDurationMillis : <num>,
   lastSessionsCollectionJobTimestamp : <Date>,
   lastSessionsCollectionJobEntriesRefreshed : <num>,
   lastSessionsCollectionJobEntriesEnded : <num>,
   lastSessionsCollectionJobCursorsClosed : <num>,
   transactionReaperJobCount : <num>,
   lastTransactionReaperJobDurationMillis : <num>,
   lastTransactionReaperJobTimestamp : <Date>,
   lastTransactionReaperJobEntriesCleanedUp : <num>,
   sessionCatalogSize : <num>
},

logicalSessionRecordCache: Provides metrics around the caching of server sessions.

logicalSessionRecordCache.activeSessionsCount

The number of all active local sessions cached in memory by the mongod or mongos instance since the last refresh period.

Tip

logicalSessionRecordCache.sessionsCollectionJobCount: The number that tracks the number of times the refresh process has run on the config.system.sessions collection.
Tip
logicalSessionRefreshMillis

logicalSessionRecordCache.lastSessionsCollectionJobDurationMillis: The length in milliseconds of the last refresh.

logicalSessionRecordCache.lastSessionsCollectionJobTimestamp: The time at which the last refresh occurred.

logicalSessionRecordCache.lastSessionsCollectionJobEntriesRefreshed: The number of sessions that were refreshed during the last refresh.

logicalSessionRecordCache.lastSessionsCollectionJobEntriesEnded: The number of sessions that ended during the last refresh.

logicalSessionRecordCache.lastSessionsCollectionJobCursorsClosed: The number of cursors that were closed during the last config.system.sessions collection refresh.

logicalSessionRecordCache.transactionReaperJobCount: The number that tracks the number of times the transaction record cleanup process has run on the config.transactions collection.

logicalSessionRecordCache.lastTransactionReaperJobDurationMillis: The length (in milliseconds) of the last transaction record cleanup.

logicalSessionRecordCache.lastTransactionReaperJobTimestamp: The time of the last transaction record cleanup.

logicalSessionRecordCache.lastTransactionReaperJobEntriesCleanedUp: The number of entries in the config.transactions collection that were deleted during the last transaction record cleanup.

logicalSessionRecordCache.sessionCatalogSize

For a mongod instance,
The size of its in-memory cache of the config.transactions entries. This corresponds to retryable writes or transactions whose sessions have not expired within the localLogicalSessionTimeoutMinutes.
For a mongos instance,
The number of the in-memory cache of its sessions that have had transactions within the most recent localLogicalSessionTimeoutMinutes interval.

mem

mem : {
   bits : <int>,
   resident : <int>,
   virtual : <int>,
   supported : <boolean>
},

mem: A document that reports on the system architecture of the mongod and current memory use.

mem.bits: A number, either 64 or 32, that indicates whether the MongoDB instance is compiled for 64-bit or 32-bit architecture.

mem.resident: The value of mem.resident is roughly equivalent to the amount of RAM, in mebibyte (MiB), currently used by the database process. During normal use, this value tends to grow. In dedicated database servers, this number tends to approach the total amount of system memory.

mem.virtual: mem.virtual displays the quantity, in mebibyte (MiB), of virtual memory used by the mongod process.

mem.supported: A boolean that indicates whether the underlying system supports extended memory information. If this value is false and the system does not support extended memory information, then other mem values may not be accessible to the database server.

mem.note

The field mem.note appears if mem.supported is false.

The mem.note field contains the text: 'not all mem info support on this platform'.

metrics

metrics : {
   abortExpiredTransactions: {
      passes: <integer>,
      successfulKills: <integer>,
      timedOutKills: <integer>
   },
   apiVersions: {
      <appName1>: <string>,
      <appName2>: <string>,
      <appName3>: <string>
   },
   aggStageCounters : {
      <aggregation stage> : Long("<num>")
   },
   changeStreams: {
      largeEventsFailed: Long("<num>"),
      largeEventsSplit: Long("<num>"),
      showExpandedEvents: Long("<num>")
   },
   commands: {
      <command>: {
         failed: Long("<num>"),
         validator: {
           total: Long("<num>"),
           failed: Long("<num>"),
           jsonSchema: Long("<num>")
         },
         total: Long("<num>"),
         rejected: Long("<num>")
      }
   },
   cursor : {
      moreThanOneBatch : Long("<num>"),
      timedOut : Long("<num>"),
      totalOpened : Long("<num>"),
      lifespan : {
         greaterThanOrEqual10Minutes : Long("<num>"),
         lessThan10Minutes : Long("<num>"),
         lessThan15Seconds : Long("<num>"),
         lessThan1Minute : Long("<num>"),
         lessThan1Second : Long("<num>"),
         lessThan30Seconds : Long("<num>"),
         lessThan5Seconds : Long("<num>")
      },
      open : {
         noTimeout : Long("<num>"),
         pinned : Long("<num>"),
         multiTarget : Long("<num>"),
         singleTarget : Long("<num>"),
         total : Long("<num>")
      }
   },
   document : {
      deleted : Long("<num>"),
      inserted : Long("<num>"),
      returned : Long("<num>"),
      updated : Long("<num>")
   },
   dotsAndDollarsFields : {
         inserts : Long("<num>"),
         updates : Long("<num>")
   },
   getLastError : {
      wtime : {
         num : <num>,
         totalMillis : <num>
      },
      wtimeouts : Long("<num>"),
      default : {
         unsatisfiable : Long("<num>"),
         wtimeouts : Long("<num>")
      }
   },
   mongos : {
      cursor : {
         moreThanOneBatch : Long("<num>"),
         totalOpened : Long("<num>")
      }
   },
   network : {  // Added in MongoDB 6.3
      totalEgressConnectionEstablishmentTimeMillis : Long("<num>"),
      totalIngressTLSConnections : Long("<num>"),
      totalIngressTLSHandshakeTimeMillis : Long("<num>"),
      totalTimeForEgressConnectionAcquiredToWireMicros : Long("<num>"),
      totalTimeToFirstNonAuthCommandMillis : Long("<num>")
      "averageTimeToCompletedTLSHandshakeMicros": Long("<num>"), // Added in MongoDB 8.2
      "averageTimeToCompletedHelloMicros": Long("<num>"), // Added in MongoDB 8.2
      "averageTimeToCompletedAuthMicros": Long("<num>") // Added in MongoDB 8.2
   },
   operation : {
      killedDueToClientDisconnect : Long("<num>"),  // Added in MongoDB 7.1
      killedDueToDefaultMaxTimeMSExpired : Long("<num>"),
      killedDueToMaxTimeMSExpired : Long("<num>"),  // Added in MongoDB 7.2
      killedDueToRangeDeletion: Long("<num>"), // Added in MongoDB 8.2
      numConnectionNetworkTimeouts : Long("<num>"),  // Added in MongoDB 6.3
      scanAndOrder : Long("<num>"),
      totalTimeWaitingBeforeConnectionTimeoutMillis : Long("<num>"),  // Added in MongoDB 6.3
      unsendableCompletedResponses : Long("<num>"),  // Added in MongoDB 7.1
      writeConflicts : Long("<num>")
   },
   operatorCounters : {
      expressions : {
         <command> : Long("<num>")
      },
      match : {
         <command> : Long("<num>")
      }
   },
   query: {
      allowDiskUseFalse: Long("<num>"),
      updateOneOpStyleBroadcastWithExactIDCount: Long("<num>"),
      bucketAuto: {
         spilledBytes: Long("<num>"),
         spilledDataStorageSize: Long("<num>"),
         spilledRecords: Long("<num>"),
         spills: Long("<num>")
      },
      lookup: {
         hashLookup: Long("<num>"),
         hashLookupSpillToDisk: Long("<num>"),
         indexedLoopJoin: Long("<num>"),
         nestedLoopJoin: Long("<num>")
      },
      multiPlanner: {
         classicCount: Long("<num>"),
         classicMicros: Long("<num>"),
         classicWorks: Long("<num>"),
         sbeCount: Long("<num>"),
         sbeMicros: Long("<num>"),
         sbeNumReads: Long("<num>"),
         histograms: {
            classicMicros: [
               { lowerBound: Long("0"), count: Long("<num>") },
               { < Additional histogram groups not shown. > },
               { lowerBound: Long("1073741824"), count: Long("<num>")> }>
            ],
            classicNumPlans: [
               { lowerBound: Long("0"), count: Long("<num>") },
               { < Additional histogram groups not shown. > },
               { lowerBound: Long("32"), count: Long("<num>") }
            ],
            classicWorks: [
               { lowerBound: Long("0"), count: Long("<num>") },
               { < Additional histogram groups not shown. > },
               { lowerBound: Long("32768"), count: Long("<num>") }
            ],
            sbeMicros: [
               { lowerBound: Long("0"), count: Long("<num>") },
               { < Additional histogram groups not shown. > },
               { lowerBound: Long("1073741824"), count: Long("<num>") }
            ],
            sbeNumPlans: [
               { lowerBound: Long("0"), count: Long("<num>") },
               { < Additional histogram groups not shown. > },
               { lowerBound: Long("32"), count: Long("<num>") }
            ],
            sbeNumReads: [
               { lowerBound: Long("0"), count: Long("<num>") },
               { < Additional histogram groups not shown. > },
               { lowerBound: Long("32768"), count: Long("<num>") }
            ]
         }
      },
      planCache: {
         classic: { hits: Long("<num>"), misses: Long("<num>"), replanned: Long("<num>") },
         sbe: { hits: Long("<num>"), misses: Long("<num>"), replanned: Long("<num>") }
      },
      queryFramework: {
         aggregate: {
            classicHybrid: Long("<num>"),
            classicOnly: Long("<num>"),
            cqf: Long("<num>"),
            sbeHybrid: Long("<num>"),
            sbeOnly: Long("<num>")
         },
         find: { classic: Long("<num>"), cqf: Long("<num>"), sbe: Long("<num>") }
      }
   },
   queryExecutor: {
      scanned : Long("<num>"),
      scannedObjects : Long("<num>"),
      collectionScans : {
         nonTailable : Long("<num>"),
         total : Long("<num>")
      },
      profiler : {
         collectionScans : {
            nonTailable : Long("<num>"),
            tailable : Long("<num>"),
            total : Long("<num>")
         }
      }
   },
   record : {
      moves : Long("<num>")
   },
   repl : {
      executor : {
         pool : {
            inProgressCount : <num>
         },
         queues : {
            networkInProgress : <num>,
            sleepers : <num>
         },
         unsignaledEvents : <num>,
         shuttingDown : <boolean>,
         networkInterface : <string>
      },
      apply : {
         attemptsToBecomeSecondary : Long("<num>"),
         batchSize: <num>,
         batches : {
            num : <num>,
            totalMillis : <num>
         },
         ops : Long("<num>")
      },
      write : {
         batchSize: <num>,
         batches : {
            num : <num>,
            totalMillis : <num>
         }
      },
      buffer : {
         write: {
            count : Long("<num>"),
            maxSizeBytes : Long("<num>"),
            sizeBytes : Long("<num>")
         },
         apply: {
            count : Long("<num>"),
            sizeBytes : Long("<num>"),
            maxSizeBytes : Long("<num>"),
            maxCount: Long("<num>")
         },
      },
      initialSync : {
         completed : Long("<num>"),
         failedAttempts : Long("<num>"),
         failures : Long("<num>")
      },
      network : {
         bytes : Long("<num>"),
         getmores : {
            num : <num>,
            totalMillis : <num>
         },
         notPrimaryLegacyUnacknowledgedWrites : Long("<num>"),
         notPrimaryUnacknowledgedWrites : Long("<num>"),
         oplogGetMoresProcessed : {
            num : <num>,
            totalMillis : <num>
         },
         ops : Long("<num>"),
         readersCreated : Long("<num>"),
         replSetUpdatePosition : {
            num : Long("<num>")
         }
      },
      reconfig : {
         numAutoReconfigsForRemovalOfNewlyAddedFields : Long("<num>")
      },
      stateTransition : {
         lastStateTransition : <string>,
         totalOperationsKilled : Long("<num>"),
         totalOperationsRunning : Long("<num>")
      },
      syncSource : {
         numSelections : Long("<num>"),
         numTimesChoseSame : Long("<num>"),
         numTimesChoseDifferent : Long("<num>"),
         numTimesCouldNotFind : Long("<num>")
      },
      waiters : {
         opTime : Long("<num>"),
         replication : Long("<num>"),
         replCoordMutexTotalWaitTimeInOplogServerStatusMillis: Long("<num>")
      }
   },
   storage : {
      freelist : {
         search : {
            bucketExhausted : <num>,
            requests : <num>,
            scanned : <num>
         }
      }
   },
   ttl : {
      deletedDocuments : Long("<num>"),
      passes : Long("<num>"),
      subPasses : Long("<num>")
   }
}

metrics: A document that returns various statistics that reflect the current use and state of a running mongod instance.

metrics.abortExpiredTransactions: Document that returns statistics on the current state of the abortExpiredTransactions thread.

metrics.abortExpiredTransactions.passes

Indicates the number of successful passes aborting transactions older than the transactionLifetimeLimitSeconds parameter.

If the passes value stops incrementing, it indicates that the abortExpiredTransactions thread may be stuck.

metrics.abortExpiredTransactions.successfulKills

Number of expired transactions successfully ended by MongoDB.

A session is checked out from a session pool to run database operations.

AbortExpiredTransactionsSessionCheckoutTimeout sets the maximum number of milliseconds for a session to be checked out when attempting to end an expired transaction.

If the expired transaction is successfully ended, MongoDB increments metrics.abortExpiredTransactions.successfulKills. If the transaction isn't successfully ended because it timed out when attempting to check out a session, MongoDB increments metrics.abortExpiredTransactions.timedOutKills.

New in version 8.1: (also available in 8.0.13)

metrics.abortExpiredTransactions.timedOutKills

Number of expired transactions unsuccessfully ended by MongoDB because it timed out when attempting to check out a session.

A session is checked out from a session pool to run database operations.

AbortExpiredTransactionsSessionCheckoutTimeout sets the maximum number of milliseconds for a session to be checked out when attempting to end an expired transaction.

New in version 8.1: (also available in 8.0.13)

metrics.aggStageCounters

A document that reports on the use of aggregation pipeline stages. The fields in metrics.aggStageCounters are the names of aggregation pipeline stages. For each pipeline stage, serverStatus reports the number of times that stage has been executed.

Updated in version 5.2 (and 5.0.6).

metrics.apiVersions

A document that contains:

The name of each client application
The Stable API version that each application was configured with within the last 24-hour period

Consider the following when viewing metrics.apiVersions:

The possible returned values for each appname are:
- default: The command was issued without a Stable API version specified.
- 1: The command was issued with Stable API version 1.
Note
You may see both return values for an appname because you can specify a Stable API version at the command level. Some of your commands may have been issued with no Stable API version, while others were issued with version 1.
API version metrics are retained for 24 hours. If no commands are issued with a specific API version from an application in the past 24 hours, that appname and API version will be removed from the metrics. This also applies to the default API version metric.
Set the appname when connecting to a MongoDB instance by specifying the appname in the connection URI. ?appName=ZZZ sets the appname to ZZZZ.
Drivers accessing the Stable API can set a default appname.
If no appname is configured, a default value will be automatically populated based on the product. For example, for a MongoDB Compass connection with no appname in the URI, the metric returns: 'MongoDB Compass': [ 'default' ].

New in version 5.0.

metrics.operatorCounters: A document that reports on the use of aggregation pipeline operators and expressions.

metrics.operatorCounters.expressions

A document with a number that indicates how often Expressions ran.

To get metrics for a specific operator, such as the greater-than operator ($gt), append the operator to the command:

db.runCommand( { serverStatus: 1 } ).metrics.operatorCounters.expressions.$gt

New in version 5.0.

metrics.operatorCounters.match

A document with a number that indicates how often match expressions ran.

Match expression operators also increment as part of an aggregation pipeline $match stage. If the $match stage uses the $expr operator, the counter for $expr increments, but the component counters do not increment.

Consider the following query:

db.matchCount.aggregate(
   [
      { $match:
         {  $expr: { $gt: [ "$_id", 0 ] } }
      }
   ]
)

The counter for $expr increments when the query runs. The counter for $gt does not.

metrics.changeStreams.largeEventsSplit: The number of change stream events larger than 16 MB that were split into smaller fragments. Events are only split if you use the $changeStreamSplitLargeEvent pipeline stage.
New in version 7.0: (Also available in 6.0.9)

metrics.changeStreams: A document that reports information about change stream events larger than 16 MB.
New in version 7.0.

metrics.changeStreams.largeEventsFailed: The number of change stream events that caused a BSONObjectTooLarge exception because the event was larger than 16 MB. To prevent the exception, see $changeStreamSplitLargeEvent.
New in version 7.0: (Also available in 6.0.9 and 5.0.19)

metrics.changeStreams.showExpandedEvents

The number of change stream cursors with the showExpandedEvents option set to true.

The counter for showExpandedEvents increments when you:

Open a change stream cursor.
Run the explain command on a change stream cursor.

New in version 7.1.

metrics.commands

A document that reports on the use of database commands. The fields in metrics.commands are the names of database commands. For each command, the serverStatus reports the total number of executions and the number of failed executions.

metrics.commands includes replSetStepDownWithForce (i.e. the replSetStepDown command with force: true) as well as the overall replSetStepDown. In earlier versions, the command reported only overall replSetStepDown metrics.

metrics.commands.<command>.failed: The number of times <command> failed on this mongod.

metrics.commands.<create or collMod>.validator: For the create and collMod commands, a document that reports on non-empty validator objects passed to the command to specify validation rules or expressions for the collection.

metrics.commands.<create or collMod>.validator.total: The number of times a non-empty validator object was passed as an option to the command on this mongod.

metrics.commands.<create or collMod>.validator.failed: The number of times a call to the command on this mongod failed with a non-empty validator object due to a schema validation error.

metrics.commands.<create or collMod>.validator.jsonSchema: The number of times a validator object with a $jsonSchema was passed as an option to the command on this mongod.

metrics.commands.<command>.total: The number of times <command> executed on this mongod.

metrics.commands.<command>.rejected

The number of times <command> was rejected on this mongod because the command or operation has an associated query setting where the reject field is true.

To set the reject field, use setQuerySettings.

New in version 8.0.

metrics.commands.update.pipeline

The number of times an aggregation pipeline was used to update documents on this mongod. Subtract this value from the total number of updates to get the number of updates made with document syntax.

The pipeline counter is only available for update and findAndModify operations.

metrics.commands.findAndModify.pipeline

The number of times findAndModify() was used in an aggregation pipeline to update documents on this mongod.

The pipeline counter is only available for update and findAndModify operations.

metrics.commands.update.arrayFilters

The number of times an arrayFilter was used to update documents on this mongod.

The arrayFilters counter is only available for update and findAndModify operations.

metrics.commands.findAndModify.arrayFilters

The number of times an arrayFilter was used with findAndModify() to update documents on this mongod.

The arrayFilters counter is only available for update and findAndModify operations.

metrics.document: A document that reflects document access and modification patterns. Compare these values to the data in the opcounters document, which track total number of operations.

metrics.document.deleted: The total number of documents deleted.

metrics.document.inserted: The total number of documents inserted.

metrics.document.returned: The total number of documents returned by queries.

metrics.document.updated: The total number of documents matched for update operations. This value is not necessarily the same as the number of documents modified by updates.

metrics.dotsAndDollarsFields

A document with a number that indicates how often insert or update operations ran using a dollar ($) prefixed name. The value does not report the exact number of operations.

When an upsert operation creates a new document, it is considered to be an insert rather than an update.

New in version 5.0.

metrics.executor: A document that reports on various statistics for the replication executor.

metrics.getLastError: A document that reports on write concern use.

metrics.getLastError.wtime: A document that reports write concern operation counts with a w argument greater than 1.

metrics.getLastError.wtime.num: The total number of operations with a specified write concern (i.e. w) that wait for one or more members of a replica set to acknowledge the write operation (i.e. a w value greater than 1.)

metrics.getLastError.wtime.totalMillis: The total amount of time in milliseconds that the mongod has spent performing write concern operations with a write concern (i.e. w) that waits for one or more members of a replica set to acknowledge the write operation (i.e. a w value greater than 1.)

metrics.getLastError.wtimeouts: The number of times that write concern operations have timed out as a result of the wtimeout threshold. This number increments for both default and non-default write concern specifications.

metrics.getLastError.default

A document that reports on when a default write concern was used (meaning, a non-clientSupplied write concern). The possible origins of a default write concern are:

implicitDefault
customDefault
getLastErrorDefaults

Refer to the following table for information on each possible write concern origin, or provenance:

Provenance	Description
`clientSupplied`	The write concern was specified in the application.
`customDefault`	The write concern originated from a custom defined default value. See `setDefaultRWConcern`.
`getLastErrorDefaults`	The write concern originated from the replica set's `settings.getLastErrorDefaults` field.
`implicitDefault`	The write concern originated from the server in absence of all other write concern specifications.

metrics.getLastError.default.unsatisfiable: Number of times that a non-clientSupplied write concern returned the UnsatisfiableWriteConcern error code.

metrics.getLastError.default.wtimeouts: Number of times a non-clientSupplied write concern timed out.

metrics.mongos: A document that contains metrics about mongos.

metrics.mongos.cursor: A document that contains metrics for cursors used by mongos.

metrics.mongos.cursor.moreThanOneBatch: The total number of cursors that have returned more than one batch since mongos started. Additional batches are retrieved using the getMore command.
New in version 5.0.

metrics.mongos.cursor.totalOpened: The total number of cursors that have been opened since mongos started, including cursors currently open. Differs from metrics.cursor.open.total, which is the number of currently open cursors only.
New in version 5.0.

metrics.network: New in version 6.3.
A document that reports server network metrics.

metrics.network.totalEgressConnectionEstablishmentTimeMillis: New in version 6.3.
The total time in milliseconds to establish server connections.

metrics.network.totalIngressTLSConnections: New in version 6.3.
The total number of incoming connections to the server that use TLS. The number is cumulative and is the total after the server was started.

metrics.network.totalIngressTLSHandshakeTimeMillis: New in version 6.3.
The total time in milliseconds that incoming connections to the server have to wait for the TLS network handshake to complete. The number is cumulative and is the total after the server was started.

metrics.network.totalTimeForEgressConnectionAcquiredToWireMicros: New in version 6.3.
The total time in microseconds that operations wait between acquisition of a server connection and writing the bytes to send to the server over the network. The number is cumulative and is the total after the server was started.

metrics.network.totalTimeToFirstNonAuthCommandMillis: New in version 6.3.
The total time in milliseconds from accepting incoming connections to the server and receiving the first operation that isn't part of the connection authentication handshake. The number is cumulative and is the total after the server was started.

metrics.network.averageTimeToCompletedTLSHandshakeMicros: New in version 8.2: (also available in 8.1.1)
The average time in microseconds that it takes to complete a TLS handshake for incoming connections.

metrics.network.averageTimeToCompletedHelloMicros: New in version 8.2: (also available in 8.1.1)
The time in microseconds between the beginning of connection establishment and the completion of the hello command. You can use this metric to tune the ingressConnectionEstablishmentMaxQueueDepth and ingressConnectionEstablishmentRatePerSec to ensure that there is proper time allotted to complete the connection establishment after exiting the queue.

metrics.network.averageTimeToCompletedAuthMicros: New in version 8.2: (also available in 8.1.1)
The time in microseconds the SASL auth exchange takes to be completed after the beginning of connection establishment.

metrics.operation: A document that holds counters for several types of update and query operations that MongoDB handles using special operation types.

metrics.operation.killedDueToClientDisconnect: New in version 7.1.
Total number of operations cancelled before completion because the client disconnected.

metrics.operation.killedDueToDefaultMaxTimeMSExpired: New in version 8.0.
Total number of operations that timed out due to the cluster-level default timeout, defaultMaxTimeMS.

metrics.operation.killedDueToMaxTimeMSExpired: New in version 7.2.
Total number of operations that timed out due to the operation-level timeout, cursor.maxTimeMS().

metrics.operation.killedDueToRangeDeletion: New in version 8.2.
Total number of operations terminated because of orphan range cleanup. To learn more, see terminateSecondaryReadsOnOrphanCleanup.

metrics.operation.numConnectionNetworkTimeouts: New in version 6.3.
Total number of operations that failed because of server connection acquisition time out errors.

metrics.operation.scanAndOrder: The total number of queries that return sorted numbers that cannot perform the sort operation using an index.

metrics.operation.totalTimeWaitingBeforeConnectionTimeoutMillis: New in version 6.3.
Total time in milliseconds that operations waited before failing because of server connection acquisition time out errors.

metrics.operation.unsendableCompletedResponses: New in version 7.1.
Total number of operations that completed server-side but did not send their response to the client because the connection between the client and server failed or disconnected.

metrics.operation.writeConflicts: The total number of queries that encountered write conflicts.

metrics.query.bucketAuto.spilledBytes: The number of in-memory bytes spilled to disk by the $bucketAuto stage.
New in version 8.2.

metrics.query.bucketAuto.spilledDataStorageSize: The total disk space, in bytes, used by the spilled data from the $bucketAuto stage.
New in version 8.2.

metrics.query.bucketAuto.spilledRecords: The number of records spilled to disk by the $bucketAuto stage.
New in version 8.2.

metrics.query.bucketAuto.spills: The number of times the $bucketAuto stage spilled to disk.
New in version 8.2.

metrics.query.lookup

A document that provides detailed data on the use of the $lookup stage with the slot-based query execution engine. To learn more, see $lookup Optimization.

These metrics are primarily intended for internal use by MongoDB.

New in version 6.1

metrics.query.multiPlanner

Provides detailed query planning data for the slot-based query execution engine and the classic query engine. For more information on the slot-based query execution engine see: Slot-Based Query Execution Engine Pipeline Optimizations.

These metrics are primarily intended for internal use by MongoDB.

New in version 6.0.0 and 5.0.9

metrics.query.sort: A document that holds counters related to sort stages.
New in version 6.2.

metrics.query.sort.spillToDisk: The total number of writes to disk caused by sort stages.
New in version 6.2.

metrics.query.sort.totalBytesSorted: The total amount of sorted data in bytes.
New in version 6.2.

metrics.query.sort.totalKeysSorted: The total number of keys used in sorts.
New in version 6.2.

query.multiPlanner.classicMicros: Aggregates the total number of microseconds spent in the classic multiplanner.

query.multiPlanner.classicWorks: Aggregates the total number of "works" performed in the classic multiplanner.

query.multiPlanner.classicCount: Aggregates the total number of invocations of the classic multiplanner.

query.multiPlanner.sbeMicros: Aggregates the total number of microseconds spent in the slot-based execution engine multiplanner.

query.multiPlanner.sbeNumReads: Aggregates the total number of reads done in the slot-based execution engine multiplanner.

query.multiPlanner.sbeCount: Aggregates the total number of invocations of the slot-based execution engine multiplanner.

query.multiPlanner.histograms.classicMicros: A histogram measuring the number of microseconds spent in an invocation of the classic multiplanner.

query.multiPlanner.histograms.classicWorks: A histogram measuring the number of "works" performed during an invocation of the classic multiplanner.

query.multiPlanner.histograms.classicNumPlans: A histogram measuring the number of plans in the candidate set during an invocation of the classic multiplanner.

query.multiPlanner.histograms.sbeMicros: A histogram measuring the number of microseconds spent in an invocation of the slot-based execution engine multiplanner.

query.multiPlanner.histograms.sbeNumReads: A histogram measuring the number of reads during an invocation of the slot-based execution engine multiplanner.

query.multiPlanner.histograms.sbeNumPlans: A histogram measuring the number of plans in the candidate set during an invocation of the slot-based execution engine multiplanner.

query.planning.fastPath.express

The number of queries that use an optimized index scan plan consisting of one of the following plan stages:

EXPRESS_CLUSTERED_IXSCAN
EXPRESS_DELETE
EXPRESS_IXSCAN
EXPRESS_UPDATE

For more information on query plans, see Explain Results.

New in version 8.1.

query.planning.fastPath.idHack: The number of queries that contain the _id field. For these queries, MongoDB uses the default index on the _id field and skips all query plan analysis.
New in version 8.1.

query.queryFramework.aggregate: A document that reports on the number of aggregation operations run on each query framework. The subfields in query.queryFramework.aggregate indicate the number of times each framework was used to perform an aggregation operation.

query.queryFramework.find: A document that reports on the number of find operations run on each query framework. The subfields in query.queryFramework.find indicate the number of times each framework was used to perform a find operation.

metrics.queryExecutor: A document that reports data from the query execution system.

metrics.queryExecutor.scanned: The total number of index items scanned during queries and query-plan evaluation. This counter is the same as totalKeysExamined in the output of explain().

metrics.queryExecutor.scannedObjects: The total number of documents scanned during queries and query-plan evaluation. This counter is the same as totalDocsExamined in the output of explain().

metrics.queryExecutor.collectionScans: A document that reports on the number of queries that performed a collection scan.

metrics.queryExecutor.collectionScans.nonTailable: The number of queries that performed a collection scan that did not use a tailable cursor.

metrics.queryExecutor.collectionScans.total: The total number queries that performed a collection scan. The total consists of queries that did and did not use a tailable cursor.

metrics.queryExecutor.profiler.collectionScans.nonTailable: The number of queries that performed a collection scan on a profile collection that did not use a tailable cursor.

metrics.queryExecutor.profiler.collectionScans.tailable: The number of queries that performed a collection scan on a profile collection that used a tailable cursor.

metrics.queryExecutor.profiler.collectionScans.total: The total number of queries that performed a collection scan on a profile collection. This includes queries that used both tailable and non-tailable cursors.

metrics.record: A document that reports on data related to record allocation in the on-disk memory files.

metrics.repl: A document that reports metrics related to the replication process. metrics.repl document appears on all mongod instances, even those that aren't members of replica sets.

metrics.repl.apply: A document that reports on the application of operations from the replication oplog.

metrics.repl.apply.batchSize

The total number of oplog operations applied. The metrics.repl.apply.batchSize is incremented with the number of operations in a batch at the batch boundaries instead of being incremented by one after each operation.

For finer granularity, see metrics.repl.apply.ops.

metrics.repl.apply.batches: metrics.repl.apply.batches reports on the oplog application process on secondaries members of replica sets. See Multithreaded Replication for more information on the oplog application processes.

metrics.repl.apply.batches.num: The total number of batches applied across all databases.

metrics.repl.apply.batches.totalMillis: The total amount of time in milliseconds the mongod has spent applying operations from the oplog.

metrics.repl.apply.ops: The total number of oplog operations applied. metrics.repl.apply.ops is incremented after each operation.
Tip
metrics.repl.apply.batchSize

metrics.repl.write: Document that reports on entries written to the oplog.
New in version 8.0.

metrics.repl.write.batchSize: Total number of entries written to the oplog. This metric updates with the number of entries in each batch as the member finishes writing the batch to the oplog.
New in version 8.0.

metrics.repl.write.batches: Document that reports on the oplog writing process for secondary members.
New in version 8.0.

metrics.repl.write.batches.num: Total number of batches written across all databases.
New in version 8.0.

metrics.repl.write.batches.totalMillis: Total time in milliseconds the member has spent writing entries to the oplog.
New in version 8.0.

metrics.repl.buffer

MongoDB buffers oplog operations from the replication sync source buffer before applying oplog entries in a batch. metrics.repl.buffer provides a way to track oplog buffers. See Multithreaded Replication for more information on the oplog application process.

Changed in version 8.0.

Starting in MongoDB 8.0, secondaries now update the local oplog and apply changes to the database in parallel. For each batch of oplog entries, MongoDB uses two buffers:

The write buffer receives new oplog entries from the primary. The writer adds these entries to the local oplog and sends them to the applier.
The apply buffer receives new oplog entries from the writer. The applier uses these entries to update the local database.

This is a breaking change as it deprecates the older metrics.repl.buffer status metrics.

metrics.repl.buffer.apply: Provides information on the status of the oplog apply buffer.
New in version 8.0.

metrics.repl.buffer.apply.count: The current number of operations in the oplog apply buffer.
New in version 8.0.

metrics.repl.buffer.apply.maxCount: Maximum number of operations in the oplog apply buffer. mongod sets this value using a constant, which is not configurable.
New in version 8.0.

metrics.repl.buffer.apply.maxSizeBytes: Maximum size of the apply buffer. mongod sets this size using a constant, which is not configurable.
New in version 8.0.

metrics.repl.buffer.apply.sizeBytes: The current size of the contents of the oplog apply buffer.
New in version 8.0.

metrics.repl.buffer.count: Deprecated since version 8.0.
Starting in MongoDB 8.0, secondaries use separate buffers to write and apply oplog entries. For the current number of operations in the oplog buffers, see the apply.count or write.count status metrics.

metrics.repl.buffer.maxSizeBytes: Deprecated since version 8.0.
Starting in MongoDB 8.0, secondaries use separate buffers to write and apply oplog entries. For the maximum size of the buffers, see the apply.maxSizeBytes or write.maxSizeBytes status metrics.

metrics.repl.buffer.sizeBytes: Deprecated since version 8.0.
Starting in MongoDB 8.0, secondaries use separate buffers to write and apply oplog entries. For the current size of the oplog buffers, see the apply.sizeBytes or write.sizeBytes status metrics.

metrics.repl.buffer.write: Provides information on the status of the oplog write buffer.
New in version 8.0.

metrics.repl.buffer.write.count: The current number of operations in the oplog write buffer.
New in version 8.0.

metrics.repl.buffer.write.maxSizeBytes: Maximum size of the write buffer. mongod sets this value using a constant, which is not configurable.
New in version 8.0.

metrics.repl.buffer.write.sizeBytes: The current size of the contents of the oplog write buffer.
New in version 8.0.

metrics.repl.network: metrics.repl.network reports network use by the replication process.

metrics.repl.network.bytes: metrics.repl.network.bytes reports the total amount of data read from the replication sync source.

metrics.repl.network.getmores: metrics.repl.network.getmores reports on the getmore operations, which are requests for additional results from the oplog cursor as part of the oplog replication process.

metrics.repl.network.getmores.num: metrics.repl.network.getmores.num reports the total number of getmore operations, which are operations that request an additional set of operations from the replication sync source.

metrics.repl.network.getmores.totalMillis: metrics.repl.network.getmores.totalMillis reports the total amount of time required to collect data from getmore operations.
Note
This number can be quite large, as MongoDB will wait for more data even if the getmore operation does not initial return data.

metrics.repl.network.getmores.numEmptyBatches

The number of empty oplog batches a secondary receives from its sync source. A secondary receives an empty batch if it is fully synced with its source and either:

The getmore times out waiting for more data, or
The sync source's majority commit point has advanced since the last batch sent to this secondary.

For a primary, if the instance was previously a secondary, the number reports on the empty batches received when it was a secondary. Otherwise, for a primary, this number is 0.

metrics.repl.network.notPrimaryLegacyUnacknowledgedWrites: The number of unacknowledged (w: 0) legacy write operations (see Opcodes) that failed because the current mongod is not in PRIMARY state.

metrics.repl.network.notPrimaryUnacknowledgedWrites: The number of unacknowledged (w: 0) write operations that failed because the current mongod is not in PRIMARY state.

metrics.repl.network.oplogGetMoresProcessed: A document that reports the number of getMore commands to fetch the oplog that a node processed as a sync source.

metrics.repl.network.oplogGetMoresProcessed.num: The number of getMore commands to fetch the oplog that a node processed as a sync source.

metrics.repl.network.oplogGetMoresProcessed.totalMillis: The time, in milliseconds, that a node spent processing the getMore commands counted in metrics.repl.network.oplogGetMoresProcessed.num.

metrics.repl.network.ops: The total number of operations read from the replication source.

metrics.repl.network.readersCreated: The total number of oplog query processes created. MongoDB will create a new oplog query any time an error occurs in the connection, including a timeout, or a network operation. Furthermore, metrics.repl.network.readersCreated will increment every time MongoDB selects a new source for replication.

metrics.repl.network.replSetUpdatePosition: A document that reports the number of replSetUpdatePosition commands a node sent to its sync source.

metrics.repl.network.replSetUpdatePosition.num: The number of replSetUpdatePosition commands a node sent to its sync source. replSetUpdatePosition commands are internal replication commands that communicate replication progress from nodes to their sync sources.
Note
Replica set members in the STARTUP2 state do not send the replSetUpdatePosition command to their sync source.

metrics.repl.reconfig: A document containing the number of times that member newlyAdded fields were automatically removed by the primary. When a member is first added to the replica set, the member's newlyAdded field is set to true.
New in version 5.0.

metrics.repl.reconfig.numAutoReconfigsForRemovalOfNewlyAddedFields: The number of times that newlyAdded member fields were automatically removed by the primary. When a member is first added to the replica set, the member's newlyAdded field is set to true. After the primary receives the member's heartbeat response indicating the member state is SECONDARY, RECOVERING, or ROLLBACK, the primary automatically removes the member's newlyAdded field. The newlyAdded fields are stored in the local.system.replset collection.
New in version 5.0.

metrics.repl.stateTransition

Information on user operations when the member undergoes one of the following transitions that can stop user operations:

The member steps up to become a primary.
The member steps down to become a secondary.
The member is actively performing a rollback.

metrics.repl.stateTransition.lastStateTransition

The transition being reported:

State Change	Description
`"stepUp"`	The member steps up to become a primary.
`"stepDown"`	The member steps down to become a secondary.
`"rollback"`	The member is actively performing a rollback.
`""`	The member has not undergone any state changes.

metrics.repl.stateTransition.totalOperationsKilled: The total number of operations stopped during the mongod instance's state change.
New in version 7.3: totalOperationsKilled replaces userOperationsKilled

metrics.repl.stateTransition.totalOperationsRunning: The total number of operations that remained running during the mongod instance's state change.
New in version 7.3: totalOperationsRunning replaces userOperationsRunning

metrics.repl.stateTransition.userOperationsKilled: Deprecated since version 7.3: totalOperationsKilled replaces userOperationsKilled.

metrics.repl.stateTransition.userOperationsRunning: Deprecated since version 7.3: totalOperationsRunning replaces userOperationsRunning.

metrics.repl.syncSource: Information on a replica set node's sync source selection process.

metrics.repl.syncSource.numSelections: Number of times a node attempted to choose a node to sync from among the available sync source options. A node attempts to choose a node to sync from if, for example, the sync source is re-evaluated or the node receives an error from its current sync source.

metrics.repl.syncSource.numTimesChoseSame: Number of times a node kept its original sync source after re-evaluating if its current sync source was optimal.

metrics.repl.syncSource.numTimesChoseDifferent: Number of times a node chose a new sync source after re-evaluating if its current sync source was optimal.

metrics.repl.syncSource.numTimesCouldNotFind: Number of times a node could not find an available sync source when attempting to choose a node to sync from.

metrics.repl.timestamps: A document that reports on the replication timestamps.
New in version 8.1.

metrics.repl.timestamps.oldestTimestamp: The timestamp for the oldest snapshot. A snapshot is a copy of the data in a mongod instance at a specific point in time.
New in version 8.1.

metrics.repl.waiters.replication: The number of threads waiting for replicated or journaled write concern acknowledgments.
New in version 7.3.

metrics.repl.waiters.opTime: The number of threads queued for local replication optime assignments.
New in version 7.3.

metrics.repl.waiters.replCoordMutexTotalWaitTimeInOplogServerStatusMillis: The average wait time in milliseconds to acquire the replication coordinator mutex. MongoDB measures this time when it generates the server status oplog section. This metric helps you identify potential replication performance issues related to mutex contention.
New in version 8.2.

metrics.storage.freelist.search.bucketExhausted: The number of times that mongod has examined the free list without finding a large record allocation.

metrics.storage.freelist.search.requests: The number of times mongod has searched for available record allocations.

metrics.storage.freelist.search.scanned: The number of available record allocations mongod has searched.

metrics.ttl: A document that reports on the operation of the resource use of the ttl index process.

metrics.ttl.deletedDocuments: The total number of documents deleted from collections with a ttl index.

metrics.ttl.invalidTTLIndexSkips

Number of TTL deletes skipped due to a TTL secondary index being present, but not valid for TTL deletion.

0 indicates all secondary TTL indexes are eligible for TTL deletion.
A non-zero value indicates there is an invalid secondary TTL index.

If there is an invalid secondary TTL index, you must manually modify the secondary index to use automatic TTL deletion.

New in version 8.1.

metrics.ttl.passes: Number of passes performed by the TTL background process to check for expired documents. A pass is complete when the TTL monitor has deleted as many candidate documents as it can find from all TTL indexes. For more information on the TTL index deletion process, see Deletion Process.

metrics.ttl.subPasses: Number of sub-passes performed by the TTL background process to check for expired documents. For more information on the TTL index deletion process, see Deletion Process.

metrics.cursor: A document that contains data regarding cursor state and use.

metrics.cursor.moreThanOneBatch: The total number of cursors that have returned more than one batch since the server process started. Additional batches are retrieved using the getMore command.
New in version 5.0.

metrics.cursor.timedOut: The total number of cursors that have timed out since the server process started. If this number is large or growing at a regular rate, this may indicate an application error.

metrics.cursor.totalOpened: The total number of cursors that have been opened since the server process started, including cursors currently open. Differs from metrics.cursor.open.total, which is the number of currently open cursors only.
New in version 5.0.

metrics.cursor.lifespan

A document that reports the number of cursors that have lifespans within specified time periods. The cursor lifespan is the time period from when the cursor is created to when the cursor is killed using the killCursors command or the cursor has no remaining objects in the batch.

The lifespan time periods are:

< 1 second
>= 1 second to < 5 seconds
>= 5 seconds to < 15 seconds
>= 15 seconds to < 30 seconds
>= 30 seconds to < 1 minute
>= 1 minute to < 10 minutes
>= 10 minutes

New in version 5.0.

metrics.cursor.lifespan.greaterThanOrEqual10Minutes: The number of cursors with a lifespan >= 10 minutes.
New in version 5.0.

metrics.cursor.lifespan.lessThan10Minutes: The number of cursors with a lifespan >= 1 minute to < 10 minutes.
New in version 5.0.

metrics.cursor.lifespan.lessThan15Seconds: The number of cursors with a lifespan >= 5 seconds to < 15 seconds.
New in version 5.0.

metrics.cursor.lifespan.lessThan1Minute: The number of cursors with a lifespan >= 30 seconds to < 1 minute.
New in version 5.0.

metrics.cursor.lifespan.lessThan1Second: The number of cursors with a lifespan < 1 second.
New in version 5.0.

metrics.cursor.lifespan.lessThan30Seconds: The number of cursors with a lifespan >= 15 seconds to < 30 seconds.
New in version 5.0.

metrics.cursor.lifespan.lessThan5Seconds: The number of cursors with a lifespan >= 1 second to < 5 seconds.
New in version 5.0.

metrics.cursor.open: A document that contains data regarding open cursors.

metrics.cursor.open.noTimeout: The number of open cursors with the option DBQuery.Option.noTimeout set to prevent timeout after a period of inactivity.

metrics.cursor.open.pinned: The number of "pinned" open cursors.

metrics.cursor.open.total: The number of cursors that MongoDB is maintaining for clients. Because MongoDB exhausts unused cursors, typically this value small or zero. However, if there is a queue, or stale tailable cursors, or a large number of operations this value may increase.

metrics.cursor.open.singleTarget: The total number of cursors that only target a single shard. Only mongos instances report metrics.cursor.open.singleTarget values.

metrics.cursor.open.multiTarget: The total number of cursors that only target more than one shard. Only mongos instances report metrics.cursor.open.multiTarget values.

mirroredReads

Available on mongod only.

"mirroredReads" : {
      "seen" : <num>,
      "sent" : <num>
},

mirroredReads

Available on mongod only.

A document that reports on mirrored reads. To return mirroredReads information, you must explicitly specify the inclusion:

db.runCommand( { serverStatus: 1, mirroredReads: 1 } )

mirroredReads.processedAsSecondary: New in version 6.2.
The number of mirrored reads processed by this member while a secondary.
Tip
mirrorReads Parameter

mirroredReads.seen: The number of operations that support mirroring received by this member.
Tip
mirrorReads Parameter

mirroredReads.sent: The number of mirrored reads sent by this member when primary. For example, if a read is mirrored and sent to two secondaries, the number of mirrored reads is 2.
Tip
mirrorReads Parameter

network

network : {
   egress : {
      bytesIn : Long("<num>"),
      bytesOut : Long("<num>"),
      physicalBytesIn : Long("<num>"),
      physicalBytesOut : Long("<num>"),
      numRequests : Long("<num>"),
   }
   bytesIn : Long("<num>"),
   bytesOut : Long("<num>"),
   physicalBytesIn : Long("<num>"),
   physicalBytesOut : Long("<num>"),
   numSlowDNSOperations : Long("<num>"),
   numSlowSSLOperations : Long("<num>"),
   numRequests : Long("<num>"),
   tcpFastOpen : {
      kernelSetting : Long("<num>"),
      serverSupported : <bool>,
      clientSupported : <bool>,
      accepted : Long("<num>")
   },
   compression : {
      snappy : {
         compressor : { bytesIn : Long("<num>"), bytesOut : Long("<num>") },
         decompressor : { bytesIn : Long("<num>"), bytesOut : Long("<num>") }
      },
      zstd : {
         compressor : { bytesIn : Long("<num>"), bytesOut : Long("<num>") },
         decompressor : { bytesIn : Long("<num>"), bytesOut : Long("<num>") }
      },
      zlib : {
         compressor : { bytesIn : Long("<num>"), bytesOut : Long("<num>") },
         decompressor : { bytesIn : Long("<num>"), bytesOut : Long("<num>") }
      }
   },
   serviceExecutors : {
      passthrough : {
         threadsRunning : <num>,
         clientsInTotal : <num>,
         clientsRunning : <num>,
         clientsWaitingForData : <num>
      },
      fixed : {
         threadsRunning : <num>,
         clientsInTotal : <num>,
         clientsRunning : <num>,
         clientsWaitingForData : <num>
      }
   },
   listenerProcessingTime : { durationMicros : <num> }  // Added in MongoDB 6.3
}

network: A document that reports data on MongoDB's network use. These statistics measure ingress and egress connections, specifically the traffic seen by the mongod or mongos over network connections initiated by clients or other mongod or mongos instances.

network.egress: Reports data on the traffic from egress connections initiated by this mongod or mongos instance. In most cases, the egress connections are mongos communicating with mongod for sharding, or mongod communicating with mongod for replication. It is also possible that mongod or mongos are communicating with external services, such as mongot.

network.egress.bytesIn: The total number of logical bytes that mongod or mongos instances have received over network connections that they have initiated to other nodes/services. Logical bytes are the exact number of bytes that a given file contains.

network.egress.bytesOut: The total number of logical bytes that mongod or mongos instances have sent over network connections that they have initiated to other nodes/services. Logical bytes correspond to the number of bytes that a given file contains.

network.egress.physicalBytesIn: The total number of physical bytes that mongod or mongos instances has received over network connections that they have initiated to other nodes/services. Physical bytes are the number of bytes that actually reside on disk.

network.egress.physicalBytesOut: The total number of physical bytes that mongod or mongos instances have sent over network connections that they have initiated to other nodes/services. Physical bytes are the number of bytes that actually reside on disk.

network.egress.numRequests: The total number of distinct requests that mongod or mongos have sent and received responses to. Use this value to provide context for the network.egress.bytesIn and network.egress.bytesOut values to ensure that MongoDB's network utilization is consistent with expectations and application use.

network.bytesIn: The total number of logical bytes that the server has received over network connections initiated by clients or other mongod or mongos instances. Logical bytes are the exact number of bytes that a given file contains.

network.bytesOut: The total number of logical bytes that the server has sent over network connections initiated by clients or other mongod or mongos instances. Logical bytes correspond to the number of bytes that a given file contains.

network.physicalBytesIn: The total number of physical bytes that the server has received over network connections initiated by clients or other mongod or mongos instances. Physical bytes are the number of bytes that actually reside on disk.

network.physicalBytesOut: The total number of physical bytes that the server has sent over network connections initiated by clients or other mongod or mongos instances. Physical bytes are the number of bytes that actually reside on disk.

network.numSlowDNSOperations: The total number of DNS resolution operations which took longer than 1 second.

network.numSlowSSLOperations: The total number of SSL handshake operations which took longer than 1 second.

network.numRequests: The total number of distinct requests that the server has received. Use this value to provide context for the network.bytesIn and network.bytesOut values to ensure that MongoDB's network utilization is consistent with expectations and application use.

network.tcpFastOpen: A document that reports data on MongoDB's support and use of TCP Fast Open (TFO) connections.

network.tcpFastOpen.kernelSetting

Linux only

Returns the value of /proc/sys/net/ipv4/tcp_fastopen:

0 - TCP Fast Open is disabled on the system.
1 - TCP Fast Open is enabled for outgoing connections.
2 - TCP Fast Open is enabled for incoming connections.
3 - TCP Fast Open is enabled for incoming and outgoing connections.

network.tcpFastOpen.serverSupported

Returns true if the host operating system supports inbound TCP Fast Open (TFO) connections.
Returns false if the host operating system does not support inbound TCP Fast Open (TFO) connections.

network.tcpFastOpen.clientSupported

Returns true if the host operating system supports outbound TCP Fast Open (TFO) connections.
Returns false if the host operating system does not support outbound TCP Fast Open (TFO) connections.

network.tcpFastOpen.accepted: The total number of accepted incoming TCP Fast Open (TFO) connections to the mongod or mongos since the mongod or mongos last started.

network.compression: A document that reports on the amount of data compressed and decompressed by each network compressor library.

network.compression.snappy: A document that returns statistics on the number of bytes that have been compressed and decompressed with the snappy library.

network.compression.zstd: A document that returns statistics on the number of bytes that have been compressed and decompressed with the zstd library.

network.compression.zlib: A document that returns statistics on the number of bytes that have been compressed and decompressed with the zlib library.

network.serviceExecutors: New in version 5.0.
A document that reports data on the service executors, which run operations for client requests.

network.serviceExecutors.passthrough: New in version 5.0.
A document that reports data about the threads and clients for the passthrough service executor. The passthrough service executor creates a new thread for each client and destroys the thread after the client ends.

network.serviceExecutors.passthrough.threadsRunning: New in version 5.0.
Number of threads running in the passthrough service executor.

network.serviceExecutors.passthrough.clientsInTotal: New in version 5.0.
Total number of clients allocated to the passthrough service executor. A client can be allocated to the passthrough service executor and not currently running requests.

network.serviceExecutors.passthrough.clientsRunning: New in version 5.0.
Number of clients currently using the passthrough service executor to run requests.

network.serviceExecutors.passthrough.clientsWaitingForData: New in version 5.0.
Number of clients using the passthrough service executor that are waiting for incoming data from the network.

network.serviceExecutors.fixed: New in version 5.0.
A document that reports data about the threads and clients for the fixed service executor. The fixed service executor has a fixed number of threads. A thread is temporarily assigned to a client and the thread is preserved after the client ends.

network.serviceExecutors.fixed.threadsRunning: New in version 5.0.
Number of threads running in the fixed service executor.

network.serviceExecutors.fixed.clientsInTotal: New in version 5.0.
Total number of clients allocated to the fixed service executor. A client can be allocated to the fixed service executor and not currently running requests.

network.serviceExecutors.fixed.clientsRunning: New in version 5.0.
Number of clients currently using the fixed service executor to run requests.

network.serviceExecutors.fixed.clientsWaitingForData: New in version 5.0.
Number of clients using the fixed service executor that are waiting for incoming data from the network.

network.listenerProcessingTime: New in version 6.3.
A document that reports the total time the database listener spends allocating incoming database connection requests to dedicated threads.

network.listenerProcessingTime.durationMicros: New in version 6.3.
Total time in microseconds the database listener spends allocating incoming database connection requests to dedicated threads that perform database operations.

opLatencies

opLatencies : {
   reads : <document>,
   writes : <document>,
   commands : <document>,
   transactions : <document>
},

opLatencies

A document containing operation latencies for the instance as a whole. See latencyStats Document for a description of this document.

Starting in MongoDB 6.2, the opLatencies metric reports for both mongod and mongos instances. Latencies reported by mongos include operation latency time and communication time between the mongod and mongos instances.

To include the histogram in the opLatencies output, run the following command:

db.runCommand( { serverStatus: 1, opLatencies: { histograms: true } } ).opLatencies

opLatencies.reads: Latency statistics for read requests.

opLatencies.writes: Latency statistics for write operations.

opLatencies.commands: Latency statistics for database commands.

opLatencies.transactions: Latency statistics for database transactions.

opWorkingTime

opWorkingTime : {
   commands : <document>,
   reads : <document>,
   writes : <document>,
   transactions : <document>
}

opWorkingTime

Document that includes information on operation execution for the instance. See latencyStats Document for a description of this document.

The fields under opWorkingTime are measured in workingMillis, which is the amount of time that MongoDB spends working on that operation. This means that factors such as waiting for locks and flow control don't affect opWorkingTime.

To include the histogram in the opWorkingTime output, run the following command:

db.runCommand( { serverStatus: 1, opWorkingTime: { histogram: true } } ).opWorkingTime

New in version 8.0.

opWorkingTime.commands: Document that reports execution statistics for database commands.
New in version 8.0.

opWorkingTime.reads: Document that reports execution statistics for read operations.
New in version 8.0.

opWorkingTime.writes: Document that reports execution statistics for write operations.
New in version 8.0.

opWorkingTime.transactions: Document that reports execution statistics for transactions.
New in version 8.0.

opReadConcernCounters

Warning

Removed

Starting in version 5.0, opReadConcernCounters is replaced by readConcernCounters.

Only for mongod instances

opReadConcernCounters : {
   available : Long("<num>"),
   linearizable : Long("<num>"),
   local : Long("<num>"),
   majority : Long("<num>"),
   snapshot : Long("<num>"),
   none : Long("<num>")
}

opReadConcernCounters

Removed in version 5.0. Replaced by readConcernCounters.

A document that reports on the read concern level specified by query operations to the mongod instance since it last started.

Specified `w`	Description
`"available"`	Number of query operations that specified read concern level `"available"`.
`"linearizable"`	Number of query operations that specified read concern level `"linearizable"`.
`"local"`	Number of query operations that specified read concern level `"local"`.
`"majority"`	Number of query operations that specified read concern level `"majority"`.
`"snapshot"`	Number of query operations that specified read concern level `"snapshot"`.
`"none"`	Number of query operations that did not specify a read concern level and instead used the default read concern level.

The sum of the opReadConcernCounters equals opcounters.query.

opWriteConcernCounters

Only for mongod instances

opWriteConcernCounters : {
   insert : {
      wmajority : Long("<num>"),
      wnum : {
         <num> :  Long("<num>"),
         ...
      },
      wtag : {
         <tag1> :  Long("<num>"),
         ...
      },
      none : Long("<num>"),
      noneInfo : {
         CWWC : {
            wmajority : Long("<num>"),
            wnum : {
               <num> :  Long("<num>"),
               ...
            },
            wtag : {
               <tag1> :  Long("<num>"),
               ...
            }
         },
         implicitDefault : {
            wmajority : Long("<num>")
            wnum : {
               <num> :  Long("<num>"),
               ...
            }
         }
      }
   },
   update : {
      wmajority : Long("<num>"),
      wnum : {
         <num> :  Long("<num>"),
         ...
      },
      wtag : {
         <tag1> :  Long("<num>"),
         ...
      },
      none : Long("<num>"),
      noneInfo : {
         CWWC : {
            wmajority : Long("<num>"),
            wnum : {
               <num> :  Long("<num>"),
               ...
            }
            wtag : {
               <tag1> :  Long("<num>"),
               ...
            }
         },
         implicitDefault : {
            wmajority : Long("<num>")
            wnum : {
               <num> :  Long("<num>"),
               ...
            }
         }
      }
   },
   delete : {
      wmajority :  Long("<num>")
      wnum : {
         <num> :  Long("<num>"),
         ...
      },
      wtag : {
         <tag1> :  Long("<num>"),
         ...
      },
      none : Long("<num>"),
      noneInfo : {
         CWWC : {
            wmajority : Long("<num>"),
            wnum : {
               <num> :  Long("<num>"),
               ...
            },
            wtag : {
               <tag1> :  Long("<num>"),
               ...
            }
         },
         implicitDefault : {
            wmajority : Long("<num>")
            wnum : {
               <num> :  Long("<num>"),
               ...
            }
         }
      }
   }
}

opWriteConcernCounters

A document that reports on the write concerns specified by write operations to the mongod instance since it last started.

More specifically, the opWriteConcernCounters reports on the w: <value> specified by the write operations. The journal flag option (j) and the timeout option (wtimeout) of the write concerns does not affect the count. The count is incremented even if the operation times out.

Note

Only available when reportOpWriteConcernCountersInServerStatus parameter is set to true (false by default).

opWriteConcernCounters.insert

A document that reports on the w: <value> specified by insert operations to the mongod instance since it last started:

Note

Only available when reportOpWriteConcernCountersInServerStatus parameter is set to true (false by default).

insert : {
   wmajority : Long("<num>"),
   wnum : {
      <num> :  Long("<num>"),
      ...
   },
   wtag : {
      <tag1> :  Long("<num>"),
      ...
   },
   none : Long("<num>"),
   noneInfo : {
      CWWC : {
         wmajority : Long("<num>"),
         wnum : {},
         wtag : {}
      },
      implicitDefault : {
         wmajority : Long("<num>")
         wnum : {}
      }
   }
},

Specified `w`	Description
`"wmajority"`	Number of insert operations that specified `w: "majority"`.
`"wnum"`	Number of insert operations that specified `w: <num>`. The counts are grouped by the specific``<num>``.
`"wtag"`	Number of insert operations that specified `w: <tag>`. The counts are grouped by the specific `<tag>`.
`"none"`	Number of insert operations that did not specify `w` value. These operations use the default `w` value of "majority".
`"noneInfo"`	Number of non-transaction query operations that use default write concerns. The metrics track usage of the `cluster wide write concern` (the global default write concern) and the implicit-default write concern. The sum of the values in `opWriteConcernCounters.noneInfo` should equal the value of `opWriteConcernCounters.none`.

The sum of the opWriteConcernCounters.insert equals opcounters.insert.

opWriteConcernCounters.update

A document that reports on the w: <value> specified by update operations to the mongod instance since it last started:

Note

Only available when reportOpWriteConcernCountersInServerStatus parameter is set to true (false by default).

update : {
   wmajority : Long("<num>"),
   wnum : {
      <num> :  Long("<num>"),
      ...
   },
   wtag : {
      <tag1> :  Long("<num>"),
      ...
   },
   none : Long("<num>"),
   noneInfo : {
      CWWC : {
         wmajority : Long("<num>"),
         wnum : {},
         wtag : {}
      },
      implicitDefault : {
         wmajority : Long("<num>")
         wnum : {}
      }
   }
},

Specified `w`	Description
`"wmajority"`	Number of update operations that specified `w: "majority"`.
`"wnum"`	Number of update operations that specified `w: <num>`. The counts are grouped by the specific `<num>`.
`"wtag"`	Number of update operations that specified `w: <tag>`. The counts are grouped by the specific `<tag>`.
`"none"`	Number of update operations that did not specify `w` value. These operations use the default `w` value of `1`.
`"noneInfo"`	Number of non-transaction query operations that use default write concerns. The metrics track usage of the `cluster wide write concern` (the global default write concern) and the implicit-default write concern. The sum of the values in `opWriteConcernCounters.noneInfo` should equal the value of `opWriteConcernCounters.none`.

The sum of the opWriteConcernCounters.update equals opcounters.update.

opWriteConcernCounters.delete

A document that reports on the w: <value> specified by delete operations to the mongod instance since it last started:

Note

Only available when reportOpWriteConcernCountersInServerStatus parameter is set to true (false by default).

delete : {
   wmajority :  Long("<num>"),
   wnum : {
      <num> :  Long("<num>"),
      ...
   },
   wtag : {
      <tag1> :  Long("<num>"),
      ...
   },
   none : Long("<num>"),
   noneInfo : {
      CWWC : {
         wmajority : Long("<num>"),
         wnum : {},
         wtag : {}
      },
      implicitDefault : {
         wmajority : Long("<num>")
         wnum : {}
      }
   }
}

Specified `w`	Description
`"wmajority"`	Number of delete operations that specified `w: "majority"`.
`"wnum"`	Number of delete operations that specified `w: <num>`. The counts are grouped by the specific `<num>`.
`"wtag"`	Number of delete operations that specified `w: <tag>`. The counts are grouped by the specific `<tag>`.
`"none"`	Number of delete operations that did not specify `w` value. These operations use the default `w` value of `1`.
`"noneInfo"`	Number of non-transaction query operations that use default write concerns. The metrics track usage of the `cluster wide write concern` (the global default write concern) and the implicit-default write concern. The sum of the values in `opWriteConcernCounters.noneInfo` should equal the value of `opWriteConcernCounters.none`.

The sum of the opWriteConcernCounters.delete equals opcounters.delete.

opcounters

opcounters : {
   insert : Long("<num>"),
   query : Long("<num>"),
   update : Long("<num>"),
   delete : Long("<num>"),
   getmore : Long("<num>"),
   command : Long("<num>"),
},

opcounters

A document that reports on database operations by type since the mongod instance last started.

These numbers will grow over time until next restart. Analyze these values over time to track database utilization.

Note

The data in opcounters treats operations that affect multiple documents, such as bulk insert or multi-update operations, as a single operation. See metrics.document for more granular document-level operation tracking.

Additionally, these values reflect received operations, and increment even when operations are not successful.

opcounters.insert: The total number of insert operations received since the mongod instance last started.

opcounters.query: The total number of queries received since the mongod instance last started. Starting in MongoDB 7.1, aggregations count as query operations and increment this value.

opcounters.update: The total number of update operations received since the mongod instance last started.

opcounters.delete: The total number of delete operations since the mongod instance last started.

opcounters.getmore: The total number of getMore operations since the mongod instance last started. This counter can be high even if the query count is low. Secondary nodes send getMore operations as part of the replication process.

opcounters.command

The total number of commands issued to the database since the mongod instance last started.

opcounters.command counts all commands except the following:

opcounters.deprecated

opQuery counts the number of requests for opcodes that are deprecated in MongoDB 5.0 but are temporarily supported. This section only appears in the db.serverStatus() output when a deprecated opcode has been used.

The counter is reset when mongod starts.

deprecated: {
   opQuery: Long("<num>"),
}

opcountersRepl

The returned opcountersRepl.* values are type NumberLong.

opcountersRepl : {
   insert : Long("<num>"),
   query : Long("<num>"),
   update : Long("<num>"),
   delete : Long("<num>"),
   getmore : Long("<num>"),
   command : Long("<num>"),
},

opcountersRepl

A document that reports on database replication operations by type since the mongod instance last started.

These values only appear when the current host is a member of a replica set.

These values will differ from the opcounters values because of how MongoDB serializes operations during replication. See Replication for more information on replication.

These numbers will grow over time in response to database use until next restart. Analyze these values over time to track database utilization.

The returned opcountersRepl.* values are type NumberLong.

opcountersRepl.insert

The total number of replicated insert operations since the mongod instance last started.

The returned opcountersRepl.* values are type NumberLong.

opcountersRepl.query

The total number of replicated queries since the mongod instance last started.

The returned opcountersRepl.* values are type NumberLong.

opcountersRepl.update

The total number of replicated update operations since the mongod instance last started.

The returned opcountersRepl.* values are type NumberLong.

opcountersRepl.delete

The total number of replicated delete operations since the mongod instance last started.

The returned opcountersRepl.* values are type NumberLong.

opcountersRepl.getmore

The total number of getMore operations since the mongod instance last started. This counter can be high even if the query count is low. Secondary nodes send getMore operations as part of the replication process.

The returned opcountersRepl.* values are type NumberLong.

opcountersRepl.command

The total number of replicated commands issued to the database since the mongod instance last started.

The returned opcountersRepl.* values are type NumberLong.

oplogTruncation

oplogTruncation : {
   totalTimeProcessingMicros : Long("<num>"),
   processingMethod : <string>,
   oplogMinRetentionHours : <double>
   totalTimeTruncatingMicros : Long("<num>"),
   truncateCount : Long("<num>")
},

oplogTruncation

A document that reports on oplog truncations.

The field only appears when the current instance is a member of a replica set and uses either the WiredTiger Storage Engine or In-Memory Storage Engine for Self-Managed Deployments.

Available in the WiredTiger Storage Engine.

oplogTruncation.totalTimeProcessingMicros

The total time taken, in microseconds, to scan or sample the oplog to determine the oplog truncation points.

totalTimeProcessingMicros is only meaningful if the mongod instance started on existing data files (i.e. not meaningful for In-Memory Storage Engine for Self-Managed Deployments).

See oplogTruncation.processingMethod

Available in the WiredTiger Storage Engine.

oplogTruncation.processingMethod

The method used at start up to determine the oplog truncation points. The value can be either "sampling" or "scanning".

processingMethod is only meaningful if the mongod instance started on existing data files (i.e. not meaningful for In-Memory Storage Engine for Self-Managed Deployments).

Available in the WiredTiger Storage Engine.

oplogTruncation.oplogMinRetentionHours

The minimum retention period for the oplog in hours. If the oplog has exceeded the oplog size, the mongod only truncates oplog entries older than the configured retention value.

Only visible if the mongod is a member of a replica set and:

The mongod was started with the --oplogMinRetentionHours command line option or the storage.oplogMinRetentionHours configuration file option,
or
The minimum retention period was configured after startup using replSetResizeOplog.

oplogTruncation.totalTimeTruncatingMicros

The cumulative time spent, in microseconds, performing oplog truncations.

Available in the WiredTiger Storage Engine.

oplogTruncation.truncateCount

The cumulative number of oplog truncations.

Available in the WiredTiger Storage Engine.

planCache

New in version 7.0.

planCache : {
   totalQueryShapes : Long("<num>"),
   totalSizeEstimateBytes : Long("<num>"),
   classic : {
      hits : Long("<num>"),
      misses : Long("<num>"),
      replanned : Long("<num>"),
      replanned_plan_is_cached_plan : Long("<num>"),
      skipped : Long("<num>")
   },
   sbe : {
      hits : Long("<num>"),
      misses: Long("<num>"),
      replanned : Long("<num>"),
      replanned_plan_is_cached_plan : Long("<num>"),
      skipped : Long("<num>")
   }
}

planCache: A document that reports query plan cache statistics.

planCache.totalQueryShapes

Approximate number of plan cache query shapes

Prior to version 7.2, information on the number of plan cache query shapes was stored in the query.planCacheTotalQueryShapes field.

New in version 7.2.

planCache.totalSizeEstimateBytes

Total size of the plan cache in bytes.

Prior to version 7.2, information on the plan cache size was stored in the query.planCacheTotalSizeEstimateBytes field.

New in version 7.2.

planCache.classic.hits: Number of classic execution engine query plans found in the query cache and reused to avoid the query planning phase.

planCache.classic.misses: Number of classic execution engine query plans which were not found in the query cache and went through the query planning phase.

planCache.classic.replanned: Number of classic execution engine query plans that were discarded and re-optimized.
New in version 8.0: (Also available in 7.0.22)

planCache.classic.replanned_plan_is_cached_plan: Number of times the server performed a replan operation for the classic execution engine that produced a plan identical to one already in the query cache.
New in version 8.2.

planCache.classic.skipped: Number of classic execution engine query plans that were not found in the query cache because the query is ineligible for caching.
New in version 7.3.

planCache.sbe.hits: Number of slot-based execution engine query plans found in the query cache and reused to avoid the query planning phase.

planCache.sbe.misses: Number of slot-based execution engine plans which were not found in the query cache and went through the query planning phase.

planCache.sbe.replanned: Number of slot-based execution engine query plans that were discarded and re-optimized.
New in version 8.0: (Also available in 7.0.22)

planCache.sbe.replanned_plan_is_cached_plan: Number of times the server performed a replan operation for the slot-based execution engine that produced a plan identical to one already in the query cache.
New in version 8.2.

planCache.sbe.skipped: Number of slot-based execution engine query plans that were not found in the query cache because the query is ineligible for caching.
New in version 7.3.

profiler

profiler: {
   totalWrites: <integer>,
   activeWriters: <integer>
}

profiler.totalWrites: Total number of writes to profile collections on all databases.

profiler.activeWriters: The instantaneous number of operations writing to a profile collection on all databases.

queryStats

New in version 7.1.

queryStats: {
   numEvicted: Long("<num>"),
   numRateLimitedRequests: Long("<num>"),
   queryStatsStoreSizeEstimateBytes: Long("<num>"),
   numQueryStatsStoreWriteErrors: Long("<num>"),
   numHmacApplicationErrors: Long("<num>")
},

queryStats: A document that contains metrics for the $queryStats aggregation stage.

queryStats.numEvicted: Number of queries that the $queryStats virtual collection has evicted due to space contraints.

queryStats.numRateLimitedRequests: Number of times that query stats were not recorded for a query due to rate limiting.

queryStats.queryStatsStoreSizeEstimateBytes: Current estimated size of objects in the $queryStats virtual collection.

queryStats.numQueryStatsStoreWriteErrors: Number of times this MongoDB process failed to store a new query stats key. Generally, these failures happen when the $queryStats virtual collection runs out of space.

queryStats.numHmacApplicationErrors: Number of times this MongoDB process failed to compute a one-way tokenized query stats key when $queryStats was called with the transformIdentifiers option.

queryAnalyzers

New in version 7.0.

queryAnalyzers: {
  activeCollections: <integer>,
  totalCollections: <integer>,
  totalSampledReadsCount: <integer>,
  totalSampledWritesCount: <integer>,
  totalSampledReadsBytes: <integer>,
  totalSampledWritesBytes: <integer>
}

queryAnalyzers.activeCollections: Number of collections the query analyzer actively samples.

queryAnalyzers.totalCollections: Total number of sampled collections.

queryAnalyzers.totalSampledReadsCount: Total number of sampled read queries.

queryAnalyzers.totalSampledWritesCount: Total number of sampled write queries.

queryAnalyzers.totalSampledReadsBytes: Total size of sampled read queries, in bytes. This metric is only available when running serverStatus on mongod.

queryAnalyzers.totalSampledWritesBytes: Total size of sampled write queries, in bytes. This metric is only available when running serverStatus on mongod.

queues

As an operation proceeds through its stages, it may enter a queue if the number of concurrent operations at the current stage exceeds a maximum threshold. This prevents excessive resource contention and provides observability into the state of the database.

New in version 8.0.

queues: {
   execution: {
      write: {
         out: Long("<num>"),
         available: Long("<num>"),
         totalTickets: Long("<num>"),
         exempt: {
            addedToQueue: Long("<num>"),
            removedFromQueue: Long("<num>"),
            queueLength: Long("<num>"),
            startedProcessing: Long("<num>"),
            processing: Long("<num>"),
            finishedProcessing: Long("<num>"),
            totalTimeProcessingMicros: Long("<num>"),
            canceled: Long("<num>"),
            newAdmissions: Long("<num>"),
            totalTimeQueuedMicros: Long("<num>")
         },
         normalPriority: {
            addedToQueue: Long("<num>"),
            removedFromQueue: Long("<num>"),
            queueLength: Long("<num>"),
            startedProcessing: Long("<num>"),
            processing: Long("<num>"),
            finishedProcessing: Long("<num>"),
            totalTimeProcessingMicros: Long("<num>"),
            canceled: Long("<num>"),
            newAdmissions: Long("<num>"),
            totalTimeQueuedMicros: Long("<num>")
         }
      },
      read: {
         out: Long("<num>"),
         available: Long("<num>"),
         totalTickets: Long("<num>"),
         exempt: {
            addedToQueue: Long("<num>"),
            removedFromQueue: Long("<num>"),
            queueLength: Long("<num>"),
            startedProcessing: Long("<num>"),
            processing: Long("<num>"),
            finishedProcessing: Long("<num>"),
            totalTimeProcessingMicros: Long("<num>"),
            canceled: Long("<num>"),
            newAdmissions: Long("<num>"),
            totalTimeQueuedMicros: Long("<num>")
         },
         normalPriority: {
            addedToQueue: Long("<num>"),
            removedFromQueue: Long("<num>"),
            queueLength: Long("<num>"),
            startedProcessing: Long("<num>"),
            processing: Long("<num>"),
            finishedProcessing: Long("<num>"),
            totalTimeProcessingMicros: Long("<num>"),
            canceled: Long("<num>"),
            newAdmissions: Long("<num>"),
            totalTimeQueuedMicros: Long("<num>")
         }
      },
      monitor: {
         timesDecreased: Long("<num>"),
         timesIncreased: Long("<num>"),
         totalAmountDecreased: Long("<num>"),
         totalAmountIncreased: Long("<num>"),
         resizeDurationMicros: Long("<num>")
      }
   },
   ingress: {
      out: Long("<num>"),
      available: Long("<num>"),
      totalTickets: Long("<num>"),
      exempt: {
         addedToQueue: Long("<num>"),
         removedFromQueue: Long("<num>"),
         queueLength: Long("<num>"),
         startedProcessing: Long("<num>"),
         processing: Long("<num>"),
         finishedProcessing: Long("<num>"),
         totalTimeProcessingMicros: Long("<num>"),
         canceled: Long("<num>"),
         newAdmissions: Long("<num>"),
         totalTimeQueuedMicros: Long("<num>")
      },
      normalPriority: {
         addedToQueue: Long("<num>"),
         removedFromQueue: Long("<num>"),
         queueLength: Long("<num>"),
         startedProcessing: Long("<num>"),
         processing: Long("<num>"),
         finishedProcessing: Long("<num>"),
         totalTimeProcessingMicros: Long("<num>"),
         canceled: Long("<num>"),
         newAdmissions: Long("<num>"),
         totalTimeQueuedMicros: Long("<num>")
      }
   },
   ingressSessionEstablishment: { // Added in MongoDB 8.2
      "addedToQueue": Long("<num>"),
      "removedFromQueue": Long("<num>"),
      "interruptedInQueue": Long("<num>")
      "rejectedAdmissions": Long("<num>"),
      "exemptedAdmissions": Long("<num>"),
      "successfulAdmissions": Long("<num>"),
      "attemptedAdmissions": Long("<num>"),
      "averageTimeQueuedMicros": Long("<num>"),
      "totalAvailableTokens": Long("<num>")
   }
}

queues.execution

New in version 8.0.

A document that returns monitoring and queue information for operations waiting to be scheduled for execution within the storage layer (concurrent transactions).

These settings are MongoDB-specific. To change the settings for concurrent reads and write transactions (read and write tickets), see storageEngineConcurrentReadTransactions and storageEngineConcurrentWriteTransactions.

Important

Starting in version 7.0, MongoDB uses a default algorithm to dynamically adjust the maximum number of concurrent storage engine transactions (including both read and write tickets) to optimize database throughput during overload.

The following table summarizes how to identify overload scenarios for MongoDB post-7.0 and for earlier releases:

Version	Diagnosing Overload Scenarios
7.0 and later	A large number of queued operations that persists for a prolonged period of time likely indicates an overload. A concurrent storage engine transaction (ticket) availability of 0 for a prolonged period of time does not indicate an overload.
6.0 and earlier	A large number of queued operations that persists for a prolonged period of time likely indicates an overload. A concurrent storage engine transaction (ticket) availibility of 0 for a prolonged period of time likely indicates an overload.

queues.execution.write: A document that returns Queue Information for concurrent write transactions (write tickets) allowed into the WiredTiger storage engine.

queues.execution.read: A document that returns Queue Information for concurrent read transactions (read tickets) allowed into the WiredTiger storage engine.

queues.execution.monitor

A document that returns monitoring metrics for adjustments that the system has made to the number of allowed concurrent transactions (tickets).

queues.execution.monitor.timesDecreased

The number of times the queue size was decreased.

queues.execution.monitor.timesIncreased

The number of times the queue size was increased.

queues.execution.monitor.totalAmountDecreased

The total amount of operations the queue decreased by.

queues.execution.monitor.totalAmountIncreased

The total number of operations the queue increased by.

queues.execution.monitor.resizeDurationMicros

The cumulative time in milliseconds that the system spent resizing the queue.

queues.ingress

New in version 8.0.

A document that returns Queue Information for ingress admission control. Use these values to protect and mitigate against resource overload by limiting the number of operations waiting for entry to the database from the network.

The maximum number of allowed concurrent operations is constrained by ingressAdmissionControllerTicketPoolSize.

queues.ingressSessionEstablishment: New in version 8.2: (also available in 8.1.1, 8.0.12, and 7.0.23)
A document that contains information about the ingress session establishment queue. This includes metrics related to connections established and processed through the connection establishment rate limiter.

queues.ingressSessionEstablishment.addedToQueue: New in version 8.2: (also available in 8.1.1, 8.0.12, and 7.0.23)
The number of incoming connections that the server adds to the ingress session establishment queue. This metric tracks connections that are processed through the rate limiter queue when the rate limiter is enabled.

queues.ingressSessionEstablishment.removedFromQueue: New in version 8.2: (also available in 8.1.1, 8.0.12, and 7.0.23)
The number of incoming connections that the server removes from the ingress session establishment queue after acquiring a connection establishment token. This metric tracks connections that have completed their wait in the rate limiter queue.

queues.ingressSessionEstablishment.interruptedInQueue: New in version 8.2: (also available in 8.1.1, 8.0.12, and 7.0.23)
The number of incoming connections that halt while waiting in the queue, typically due to client disconnects or server shutdown.

queues.ingressSessionEstablishment.rejectedAdmissions: New in version 8.2: (also available in 8.1.1, 8.0.12, and 7.0.23)
The number of incoming connection attempts that the server rejects because the queue depth exceeded the ingressConnectionEstablishmentMaxQueueDepth limit. When this happens, the server immediately closes the connection rather than queuing it.

queues.ingressSessionEstablishment.exemptedAdmissions: New in version 8.2: (also available in 8.1.1, 8.0.12, and 7.0.23)
The number of incoming connection attempts that bypass the rate limiter due to being on the ingressConnectionEstablishmentRateLimiterBypass list. Connections from IP addresses or CIDR ranges specified in ingressConnectionEstablishmentRateLimiterBypass are not subject to rate limiting.

queues.ingressSessionEstablishment.successfulAdmissions: New in version 8.2: (also available in 8.1.1, 8.0.12, and 7.0.23)
The total number of incoming connection attempts that the rate limiter successfully processes, either immediately or after waiting in the queue.

queues.ingressSessionEstablishment.attemptedAdmissions: New in version 8.2: (also available in 8.1.1, 8.0.12, and 7.0.23)
The total number of incoming connection attempts on the rate limiter.

queues.ingressSessionEstablishment.averageTimeQueuedMicros: New in version 8.2: (also available in 8.1.1, 8.0.12, and 7.0.23)
The average time in microseconds that connections spend waiting in the queue before the server processes them. This metric uses an exponentially-weighted moving average formula and can be used to tune the ingressConnectionEstablishmentMaxQueueDepth. The value roughly equals (maxQueueDepth / establishRatePerSec) * 1e6.

queues.ingressSessionEstablishment.totalAvailableTokens: New in version 8.2: (also available in 8.1.1, 8.0.12, and 7.0.23)
The current number of available tokens in the token bucket. This represents the capacity for immediately processing new connections without queuing. When this value is 0, new connections must wait in the queue, or are rejected if the queue is full.

Queue Information

out: Long("<num>"),
available: Long("<num>"),
totalTickets: Long("<num>"),
exempt: {
   addedToQueue: Long("<num>"),
   removedFromQueue: Long("<num>"),
   queueLength: Long("<num>"),
   startedProcessing: Long("<num>"),
   processing: Long("<num>"),
   finishedProcessing: Long("<num>"),
   totalTimeProcessingMicros: Long("<num>"),
   canceled: Long("<num>"),
   newAdmissions: Long("<num>"),
   totalTimeQueuedMicros: Long("<num>")
},
normalPriority: {
   addedToQueue: Long("<num>"),
   removedFromQueue: Long("<num>"),
   queueLength: Long("<num>"),
   startedProcessing: Long("<num>"),
   processing: Long("<num>"),
   finishedProcessing: Long("<num>"),
   totalTimeProcessingMicros: Long("<num>"),
   canceled: Long("<num>"),
   newAdmissions: Long("<num>"),
   totalTimeQueuedMicros: Long("<num>")
}

out: The number of currently held tickets.

available: The number of available tickets.

totalTickets: The size of the ticket pool.

exempt: A document that returns metrics for operations exempt from the queue.

exempt.startedProcessing: The total number of operations that acquired an admission ticket.

exempt.processing: The total number of operations that are currently being processed.

exempt.finishedProcessing: The total number of operations that released their admission ticket.

exempt.totalTimeProcessingMicros: The total time operations held their admission tickets.

exempt.canceled: The total number of operations that timed out in the queue.

exempt.newAdmissions: The total number of new admissions to the queue.

exempt.totalTimeQueuedMicros: The total time operations spent waiting on the queue.

normalPriority: A document that returns metrics for operations subject to the queue.

normalPriority.addedToQueue: The total number of operations added to the queue.

normalPriority.removedFromQueue: The total number of operations removed from the queue.

normalPriority.queueLength: The total number of operations in the queue.

normalPriority.startedProcessing: The total number of operations that acquired an admission ticket.

normalPriority.processing: The total number of operations that are currently being processed.

normalPriority.finishedProcessing: The total number of operations that released their admission ticket.

normalPriority.totalTimeProcessingMicros: The total time operations held their admission tickets.

normalPriority.canceled: The total number of operations that timed out in the queue.

normalPriority.newAdmissions: The total number of new admissions to the queue.

normalPriority.totalTimeQueuedMicros: The total time operations spent waiting on the queue.

querySettings

New in version 8.0.

querySettings: {
  count: <num>,
  rejectCount: <num>,
  size: <num>
}

querySettings

Document with configuration counts and usage for query settings.

Starting in MongoDB 8.0, use query settings instead of adding index filters. Index filters are deprecated starting in MongoDB 8.0.

Query settings have more functionality than index filters. Also, index filters aren't persistent and you cannot easily create index filters for all cluster nodes. To add query settings and explore examples, see setQuerySettings.

querySettings.count: Total number of query settings.

querySettings.rejectCount: Total number of query settings that have the reject field set to true. To set the reject field, use setQuerySettings.

querySettings.size: Total size in bytes for query settings.

readConcernCounters

New in version 5.0.

readConcernCounters : {
   nonTransactionOps : {
      none : Long("<num>"),
      noneInfo : {
         CWRC : {
            local : Long("<num>"),
            available : Long("<num>"),
            majority : Long("<num>")
         },
         implicitDefault : {
            local : Long("<num>"),
            available : Long("<num>")
         }
      },
      local : Long("<num>"),
      available : Long("<num>"),
      majority : Long("<num>"),
      snapshot : {
         withClusterTime : Long("<num>"),
         withoutClusterTime : Long("<num>")
      },
      linearizable : Long("<num>")
   },
   transactionOps : {
      none : Long("<num>"),
      noneInfo : {
         CWRC : {
            local : Long("<num>"),
            available : Long("<num>"),
            majority : Long("<num>")
         },
         implicitDefault : {
            local : Long("<num>"),
            available : Long("<num>")
         }
      },
      local : Long("<num>"),
      majority : Long("<num>"),
      snapshot : {
         withClusterTime : Long("<num>"),
         withoutClusterTime : Long("<num>")
      }
   }
},

readConcernCounters: A document that reports on the read concern level specified by query operations. This document contains the readConcernCounters.nonTransactionOps and readConcernCounters.transactionOps documents.

readConcernCounters.nonTransactionOps: A document that reports on the read concern level specified by non-transaction query operations performed after the database server last started.

readConcernCounters.nonTransactionOps.none

Number of non-transaction query operations that did not specify a read concern level and instead used either:

the default read concern level, or
the global default read concern configuration if it was set by the setDefaultRWConcern command.

readConcernCounters.nonTransactionOps.noneInfo

The number of non-transaction query operations that use the global default read concern and an implicit-default read concern.

The sum of the values in readConcernCounters.nonTransactionOps.noneInfo should equal the value of readConcernCounters.nonTransactionOps.none.

readConcernCounters.nonTransactionOps.local: Number of non-transaction query operations that specified the "local" read concern level.

readConcernCounters.nonTransactionOps.available: Number of non-transaction query operations that specified the "available" read concern level.

readConcernCounters.nonTransactionOps.majority: Number of non-transaction query operations that specified the "majority" read concern level.

readConcernCounters.nonTransactionOps.snapshot: Document containing non-transaction query operations that specified the "snapshot" read concern level.

readConcernCounters.nonTransactionOps.snapshot.withClusterTime: Number of non-transaction query operations that specified the "snapshot" read concern level and the cluster time, which specified a point in time.

readConcernCounters.nonTransactionOps.snapshot.withoutClusterTime: Number of non-transaction query operations that specified the "snapshot" read concern level without the cluster time, which means a point in time was omitted and the server will read the most recently committed snapshot available to the node.

readConcernCounters.nonTransactionOps.linearizable: Number of non-transaction query operations that specified the "linearizable" read concern level.

readConcernCounters.transactionOps: A document that reports on the read concern level specified by transaction query operations performed after the database server last started.

readConcernCounters.transactionOps.none: Number of transaction query operations that did not specify a read concern level and instead used the default read concern level or the global default read or write concern configuration added with the setDefaultRWConcern command.

readConcernCounters.transactionOps.noneInfo: Information about the global default read concern and implicit-default read concern used by transaction query operations.

readConcernCounters.transactionOps.local: Number of transaction query operations that specified the "local" read concern level.

readConcernCounters.transactionOps.available: Number of transaction query operations that specified the "available" read concern level.

readConcernCounters.transactionOps.majority: Number of transaction query operations that specified the "majority" read concern level.

readConcernCounters.transactionOps.snapshot: Document containing transaction query operations that specified the "snapshot" read concern level.

readConcernCounters.transactionOps.snapshot.withClusterTime: Number of transaction query operations that specified the "snapshot" read concern level and the cluster time, which specified a point in time.

readConcernCounters.transactionOps.snapshot.withoutClusterTime: Number of transaction query operations that specified the "snapshot" read concern level without the cluster time, which means a point in time was omitted and the server will read the most recently committed snapshot available to the node.

readPreferenceCounters

Available starting in MongoDB 7.2 (and 7.0.3, 6.0.11).

Available on mongod only.

readPreferenceCounters : {
   executedOnPrimary : {
      primary : {
         internal : Long("<num>"),
         external : Long("<num>")
      },
      primaryPreferred : {
         internal : Long("<num>"),
         external : Long("<num>")
      },
      secondary : {
         internal : Long("<num>"),
         external : Long("<num>")
      },
      secondaryPreferred : {
         internal : Long("<num>"),
         external : Long("<num>")
      },
      nearest : {
         internal : Long("<num>"),
         external : Long("<num>")
      },
      tagged : {
         internal : Long("<num>"),
         external : Long("<num>")
      }
   },
   executedOnSecondary : {
      primary : {
         internal : Long("<num>"),
         external : Long("<num>")
      },
      primaryPreferred : {
         internal : Long("<num>"),
         external : Long("<num>")
      },
      secondary : {
         internal : Long("<num>"),
         external : Long("<num>")
      },
      secondaryPreferred : {
         internal : Long("<num>"),
         external : Long("<num>")
      },
      nearest : {
         internal : Long("<num>"),
         external : Long("<num>")
      },
      tagged : {
         internal : Long("<num>"),
         external : Long("<num>")
      }
   }
}

readPreferenceCounters

Available on mongod only.

A document that reports the number of operations received by this mongod node with the specified read preference.

The tagged sub-field refers to any read preference passed in with a tag.

readPreferenceCounters.executedOnPrimary

Available on mongod only.

A document that counts how many internal and external read preference operations the node received while serving as the primary.

readPreferenceCounters.executedOnSecondary

Available on mongod only.

A document that counts how many internal and external read preference operations the node received while serving as a secondary.

repl

repl : {
   hosts : [
         <string>,
         <string>,
         <string>
   ],
   setName : <string>,
   setVersion : <num>,
   isWritablePrimary : <boolean>,
   secondary : <boolean>,
   primary : <hostname>,
   me : <hostname>,
   electionId : ObjectId(""),
   userWriteBlockReason : <num>,
   userWriteBlockModeCounters: {
      Unspecified: <num>,
      ClusterToClusterMigrationInProgress: <num>,
      DiskUseThresholdExceeded: <num>
   },
   primaryOnlyServices: {
      ReshardingRecipientService: { state: <string>, numInstances: <num> },
      RenameCollectionParticipantService: { state: <string>, numInstances: <num> },
      ShardingDDLCoordinator: { state: <string>, numInstances: <num> },
      ReshardingDonorService: { state: <string>, numInstances: <num> }
   },
   rbid : <num>,
   replicationProgress : [
         {
            rid : <ObjectId>,
            optime : { ts: <timestamp>, term: <num> },
            host : <hostname>,
            memberId : <num>
         },
        ...
   ]
   timestamps : {
      oldestTimestamp: <timestamp>
   }
}

repl: A document that reports on the replica set configuration. repl only appear when the current host is a replica set. See Replication for more information on replication.

repl.hosts: An array of the current replica set members' hostname and port information ("host:port").

repl.setName: A string with the name of the current replica set. This value reflects the --replSet command line argument, or replSetName value in the configuration file.

repl.isWritablePrimary: A boolean that indicates whether the current node is the primary of the replica set.

repl.secondary: A boolean that indicates whether the current node is a secondary member of the replica set.

repl.primary: The hostname and port information ("host:port") of the current primary member of the replica set.

repl.me: The hostname and port information ("host:port") for the current member of the replica set.

repl.userWriteBlockReason

A numeric value that represents the reason why user writes are blocked. This field is relevant only when you set userWriteBlockMode to 2 to enable write-blocking.

Possible values are:

0: Unspecified
1: ClusterToClusterMigrationInProgress
2: DiskUseThresholdExceeded

This field corresponds to the reason parameter specified in the setUserWriteBlockMode command when write-blocking is enabled.

repl.userWriteBlockModeCounters: A document that contains counters tracking the number of times write-blocking is enabled with different reasons since the server started.

repl.userWriteBlockModeCounters.Unspecified: The number of times write-blocking is enabled with the reason Unspecified since the server started.

repl.userWriteBlockModeCounters.ClusterToClusterMigrationInProgress: The number of times write-blocking is enabled with the reason ClusterToClusterMigrationInProgress since the server started.

repl.userWriteBlockModeCounters.DiskUseThresholdExceeded: The number of times write-blocking is enabled with the reason DiskUseThresholdExceeded since the server started.

repl.primaryOnlyServices: Document that contains the number and status of instances of each primary service active on the server. Primary services can only start when a server is primary but can continue running to completion after the server changes state.
New in version 5.0.

repl.primaryOnlyServices.ReshardingRecipientService

Document that contains the state and number of instances of the ReshardingRecipientService.

Recipients are the shards,that would own the chunks after as a result of the resharding operation, according to the new shard key and zones.

The resharding coordinator instructs each donor and recipient shard primary, to rename the temporary sharded collection. The temporary collection becomes the new resharded collection.

New in version 5.0.

repl.primaryOnlyServices.RenameCollectionParticipantService

Document that contains the state and number of instances of the RenameCollectionParticipantService.

The RenameCollectionParticipantService ensures that, after a shard receives a renameCollection request, the shard is able to resume the local rename in case of system failure.

New in version 5.0.

repl.primaryOnlyServices.ShardingDDLCoordinator

Document that contains the state and number of instances of the ShardingDDLCoordinator.

The ShardingDDLCoordinator service manages DDL operations for primary databases such as: create database, drop database, renameCollection.

The ShardingDDLCoordinator ensures that one DDL operation for each database can happen at any one specific point in time within a sharded cluster.

New in version 5.0.

repl.primaryOnlyServices.ReshardingDonorService

Document that contains the state and number of instances of the ReshardingDonorService.

Donors are the shards that own chunks of the sharded collection before the rename operation completes.

The resharding coordinator instructs each donor and recipient shard primary, to rename the temporary sharded collection. The temporary collection becomes the new resharded collection.

New in version 5.0.

repl.rbid: Rollback identifier. Used to determine if a rollback has happened for this mongod instance.

repl.replicationProgress

An array with one document for each member of the replica set that reports replication process to this member. Typically this is the primary, or secondaries if using chained replication.

To include this output, you must pass the repl option to the serverStatus, as in the following:

db.serverStatus({ "repl": 1 })
db.runCommand({ "serverStatus": 1, "repl": 1 })

The content of the repl.replicationProgress section depends on the source of each member's replication. This section supports internal operation and is for internal and diagnostic use only.

repl.replicationProgress[n].rid: An ObjectId used as an ID for the members of the replica set. For internal use only.

repl.replicationProgress[n].optime: Information regarding the last operation from the oplog that the member applied, as reported from this member.

repl.replicationProgress[n].host: The name of the host in [hostname]:[port] format for the member of the replica set.

repl.replicationProgress[n].memberID: The integer identifier for this member of the replica set.

security

security : {
   authentication : {
      saslSupportedMechsReceived : <num>,
      mechanisms : {
         MONGODB-X509 : {
            speculativeAuthenticate : {
               received : Long("<num>"),
               successful : Long("<num>")
            },
            authenticate : {
               received : Long("<num>"),
               successful : Long("<num>")
            }
         },
         SCRAM-SHA-1 : {
            speculativeAuthenticate : {
               received : Long("<num>"),
               successful : Long("<num>")
            },
            authenticate : {
               received : Long("<num>"),
               successful : Long("<num>")
            }
         },
         SCRAM-SHA-256 : {
            speculativeAuthenticate : {
               received : Long("<num>"),
               successful : Long("<num>")
            },
            authenticate : {
               received : Long("<num>"),
               successful : Long("<num>")
            }
          }
       }
     },
     SSLServerSubjectName: <string>,
     SSLServerHasCertificateAuthority: <boolean>,
     SSLServerCertificateExpirationDate: <date>
},

security

A document that reports on:

The number of times a given authentication mechanism has been used to authenticate against the mongod or mongos instance.
The mongod / mongos instance's TLS/SSL certificate. (Only appears for mongod or mongos instance with support for TLS)

security.authentication.saslSupportedMechsReceived: New in version 5.0.
The number of times a hello request includes a valid hello.saslSupportedMechs field.

security.authentication.mechanisms: A document that reports on the number of times a given authentication mechanism has been used to authenticate against the mongod or mongos instance. The values in the document distinguish standard authentication and speculative authentication. [1]
Note
The fields in the mechanisms document depend on the configuration of the authenticationMechanisms parameter. The mechanisms document includes a field for each authentication mechanism supported by your mongod or mongos instance.
The following example shows the shape of the mechanisms document for a deployment that only supports X.509 authentication.

security.authentication.mechanisms.MONGODB-X509

A document that reports on the number of times X.509 has been used to authenticate against the mongod or mongos instance.

Includes total number of X.509 authentication attempts and the subset of those attempts which were speculative. [1]

security.authentication.mechanisms.MONGODB-X509.speculativeAuthenticate.received: Number of speculative authentication attempts received using X.509. Includes both successful and failed speculative authentication attempts. [1]

security.authentication.mechanisms.MONGODB-X509.speculativeAuthenticate.successful: Number of successful speculative authentication attempts received using X.509. [1]

security.authentication.mechanisms.MONGODB-X509.authenticate.received: Number of successful and failed authentication attempts received using X.509. This value includes speculative authentication attempts received using X.509.

security.authentication.mechanisms.MONGODB-X509.authenticate.successful: Number of successful authentication attempts received using x.508. This value includes successful speculative authentication attempts which used X.509.

[1]	(1, 2, 3, 4) Speculative authentication minimizes the number of network round trips during the authentication process to optimize performance.

security.SSLServerSubjectName: The subject name associated with the mongod / mongos instance's TLS/SSL certificate.

security.SSLServerHasCertificateAuthority

A boolean that is:

true when the mongod / mongos instance's TLS/SSL certificate is associated with a certificate authority.
false when the TLS/SSL certificate is self-signed.

security.SSLServerCertificateExpirationDate: The expiration date and time of the mongod / mongos instance's TLS/SSL certificate.

sharding

{
   configsvrConnectionString : 'csRS/cfg1.example.net:27019,cfg2.example.net:27019,cfg2.example.net:27019',
   lastSeenConfigServerOpTime : {
      ts : <timestamp>,
      t : Long("<num>")
   },
   maxChunkSizeInBytes : Long("<num>")
}

sharding: A document with data regarding the sharded cluster. The lastSeenConfigServerOpTime is present only for a mongos or a shard member, not for a config server.

sharding.configsvrConnectionString: The connection string for the config servers.

sharding.lastSeenConfigServerOpTime

The latest optime of the CSRS primary that the mongos or the shard member has seen. The optime document includes:

ts, the Timestamp of the operation.
t, the term in which the operation was originally generated on the primary.

The lastSeenConfigServerOpTime is present only if the sharded cluster uses CSRS.

sharding.maxChunkSizeInBytes: The maximum size limit for a range to migrate. If this value has been updated recently on the config server, the maxChunkSizeInBytes may not reflect the most recent value.

shardingStatistics

When run on a member of a shard:

shardingStatistics : {
   countStaleConfigErrors : Long("<num>"),
   countDonorMoveChunkStarted : Long("<num>"),
   countDonorMoveChunkCommitted : Long("<num>"),
   countDonorMoveChunkAborted : Long("<num>"),
   totalDonorMoveChunkTimeMillis : Long("<num>"),
   totalDonorChunkCloneTimeMillis : Long("<num>"),
   totalCriticalSectionCommitTimeMillis : Long("<num>"),
   totalCriticalSectionTimeMillis : Long("<num>"),
   countDocsClonedOnRecipient : Long("<num>"),
   countBytesClonedOnRecipient : Long("<num>"),
   countDocsClonedOnCatchUpOnRecipient : Long("<num>"),
   countBytesClonedOnCatchUpOnRecipient : Long("<num>"),
   countDocsClonedOnDonor : Long("<num>"),
   countRecipientMoveChunkStarted : Long("<num>"),
   countDocsDeletedByRangeDeleter : Long("<num>"),
   countDonorMoveChunkLockTimeout : Long("<num>"),
   unfinishedMigrationFromPreviousPrimary : Long("<num>"),
   chunkMigrationConcurrency : Long("<num>"),
   countTransitionToDedicatedConfigServerStarted : Long("<num>"), // Added in MongoDB 8.0
   countTransitionToDedicatedConfigServerCompleted : Long("<num>"), // Added in MongoDB 8.0
   countTransitionFromDedicatedConfigServerCompleted : Long("<num>"), // Added in MongoDB 8.0
   catalogCache : {
      numDatabaseEntries : Long("<num>"),
      numCollectionEntries : Long("<num>"),
      countStaleConfigErrors : Long("<num>"),
      totalRefreshWaitTimeMicros : Long("<num>"),
      numActiveIncrementalRefreshes : Long("<num>"),
      countIncrementalRefreshesStarted : Long("<num>"),
      numActiveFullRefreshes : Long("<num>"),
      countFullRefreshesStarted : Long("<num>"),
      countFailedRefreshes : Long("<num>")
   },
   rangeDeleterTasks : <num>,
   configServerInShardCache : <boolean>, // Added in MongoDB 8.0
   resharding : {
      countStarted : Long("1"),
       countSucceeded : Long("1"),
       countFailed : Long("0"),
       countCanceled : Long("0"),
       lastOpEndingChunkImbalance : Long("0"),
       active : {
               documentsCopied : Long("0"),
               bytesCopied : Long("0"),
               countWritesToStashCollections : Long("0"),
               countWritesDuringCriticalSection : Long("0"),
               countReadsDuringCriticalSection : Long("0"),
               oplogEntriesFetched : Long("0"),
               oplogEntriesApplied : Long("0"),
               insertsApplied : Long("0"),
               updatesApplied : Long("0"),
               deletesApplied : Long("0")
       },
       oldestActive : {
               coordinatorAllShardsHighestRemainingOperationTimeEstimatedMillis : Long("0"),
               coordinatorAllShardsLowestRemainingOperationTimeEstimatedMillis : Long("0"),
               recipientRemainingOperationTimeEstimatedMillis : Long("0")
       },
       latencies : {
               collectionCloningTotalRemoteBatchRetrievalTimeMillis : Long("0"),
               collectionCloningTotalRemoteBatchesRetrieved : Long("0"),
               collectionCloningTotalLocalInsertTimeMillis : Long("0"),
               collectionCloningTotalLocalInserts : Long("0"),
               oplogFetchingTotalRemoteBatchRetrievalTimeMillis : Long("0"),
               oplogFetchingTotalRemoteBatchesRetrieved : Long("0"),
               oplogFetchingTotalLocalInsertTimeMillis : Long("0"),
               oplogFetchingTotalLocalInserts : Long("0"),
               oplogApplyingTotalLocalBatchRetrievalTimeMillis : Long("0"),
               oplogApplyingTotalLocalBatchesRetrieved : Long("0"),
               oplogApplyingTotalLocalBatchApplyTimeMillis : Long("0"),
               oplogApplyingTotalLocalBatchesApplied : Long("0")
       },
       currentInSteps : {
               countInstancesInCoordinatorState1Initializing : Long("0"),
               countInstancesInCoordinatorState2PreparingToDonate : Long("0"),
               countInstancesInCoordinatorState3Cloning : Long("0"),
               countInstancesInCoordinatorState4Applying : Long("0"),
               countInstancesInCoordinatorState5BlockingWrites : Long("0"),
               countInstancesInCoordinatorState6Aborting : Long("0"),
               countInstancesInCoordinatorState7Committing : Long("-1"),
               countInstancesInRecipientState1AwaitingFetchTimestamp : Long("0"),
               countInstancesInRecipientState2CreatingCollection : Long("0"),
               countInstancesInRecipientState3Cloning : Long("0"),
               countInstancesInRecipientState4Applying : Long("0"),
               countInstancesInRecipientState5Error : Long("0"),
               countInstancesInRecipientState6StrictConsistency : Long("0"),
               countInstancesInRecipientState7Done : Long("0"),
               countInstancesInDonorState1PreparingToDonate : Long("0"),
               countInstancesInDonorState2DonatingInitialData : Long("0"),
               countInstancesInDonorState3DonatingOplogEntries : Long("0"),
               countInstancesInDonorState4PreparingToBlockWrites : Long("0"),
               countInstancesInDonorState5Error : Long("0"),
               countInstancesInDonorState6BlockingWrites : Long("0"),
               countInstancesInDonorState7Done : Long("0")
       }
    }
   }
},

When run on a mongos:

shardingStatistics : {
   numHostsTargeted: {
      find : {
         allShards: Long("<num>"),
         manyShards: Long("<num>"),
         oneShard: Long("<num>"),
         unsharded: Long("<num>")
               },
      insert: {
         allShards: Long("<num>"),
         manyShards: Long("<num>"),
         oneShard: Long("<num>"),
         unsharded: Long("<num>")
               },
      update: {
         allShards: Long("<num>"),
         manyShards: Long("<num>"),
         oneShard: Long("<num>"),
         unsharded: Long("<num>")
               },
      delete: {
         allShards: Long("<num>"),
         manyShards: Long("<num>"),
         oneShard: Long("<num>"),
         unsharded: Long("<num>")
               },
      aggregate: {
         allShards: Long("<num>"),
         manyShards: Long("<num>"),
         oneShard: Long("<num>"),
         unsharded: Long("<num>")
               }
      }
   },
   catalogCache : {
      numDatabaseEntries : Long("<num>"),
      numCollectionEntries : Long("<num>"),
      countStaleConfigErrors : Long("<num>"),
      totalRefreshWaitTimeMicros : Long("<num>"),
      numActiveIncrementalRefreshes : Long("<num>"),
      countIncrementalRefreshesStarted : Long("<num>"),
      numActiveFullRefreshes : Long("<num>"),
      countFullRefreshesStarted : Long("<num>"),
      countFailedRefreshes : Long("<num>")
   },
   configServerInShardCache : <boolean> // Added in MongoDB 8.0
}

shardingStatistics: A document which contains metrics on metadata refresh on sharded clusters.

shardingStatistics.countStaleConfigErrors

The total number of times that threads hit stale config exception. Since a stale config exception triggers a refresh of the metadata, this number is roughly proportional to the number of metadata refreshes.

Only present when run on a shard.

shardingStatistics.countDonorMoveChunkStarted

The total number of times that MongoDB starts the moveChunk command or moveRange command on the primary node of the shard as part of the range migration procedure. This increasing number does not consider whether the chunk migrations succeed or not.

Only present when run on a shard.

shardingStatistics.countDonorMoveChunkCommitted

The total number of chunk migrations that MongoDB commits on the primary node of the shard.

The chunk migration is performed by moveChunk and moveRange commands in a range migration procedure.

Only available on a shard.

Available starting in MongoDB 7.1 (and 7.0, 6.3.2, 6.0.6, and 5.0.18).

shardingStatistics.countDonorMoveChunkAborted

The total number of chunk migrations that MongoDB aborts on the primary node of the shard.

The chunk migration is performed by moveChunk and moveRange commands in a range migration procedure.

Only available on a shard.

Available starting in MongoDB 7.1 (and 7.0, 6.3.2, 6.0.6, and 5.0.18).

shardingStatistics.totalDonorMoveChunkTimeMillis

Cumulative time in milliseconds to move chunks from the current shard to another shard. For each chunk migration, the time starts when a moveRange or moveChunk command starts, and ends when the chunk is moved to another shard in a range migration procedure.

Only available on a shard.

Available starting in MongoDB 7.1 (and 7.0, 6.3.2, 6.0.6, and 5.0.18).

shardingStatistics.totalDonorChunkCloneTimeMillis

The cumulative time, in milliseconds, that the clone phase of the range migration procedure takes on the primary node of the shard. Specifically, for each migration on this shard, the tracked time starts with the moveRange and moveChunk commands and ends before the destination shard enters a catchup phase to apply changes that occurred during the range migration procedure.

Only present when run on a shard.

shardingStatistics.totalCriticalSectionCommitTimeMillis

The cumulative time, in milliseconds, that the update metadata phase of the range migrations procedure takes on the primary node of the shard. During the update metadata phase, MongoDB blocks all operations on the collection.

Only present when run on a shard.

shardingStatistics.totalCriticalSectionTimeMillis

The cumulative time, in milliseconds, that the catch-up phase and the update metadata phase of the range migration procedure takes on the primary node of the shard.

To calculate the duration of the catch-up phase, subtract totalCriticalSectionCommitTimeMillis from totalCriticalSectionTimeMillis:

totalCriticalSectionTimeMillis - totalCriticalSectionCommitTimeMillis

Only present when run on a shard.

shardingStatistics.countDocsClonedOnRecipient

The cumulative, always-increasing count of documents that MongoDB clones on the primary node of the recipient shard.

Only present when run on a shard.

shardingStatistics.countBytesClonedOnRecipient

The cumulative number of bytes that MongoDB clones on the primary node of the recipient shard during the range migration procedure.

For details about data synchronization, see Replica Set Data Synchronization.

Only available on a shard.

Available starting in MongoDB 7.1 (and 7.0, 6.3.2, 6.0.6, and 5.0.18).

shardingStatistics.countDocsClonedOnCatchUpOnRecipient

The cumulative number of documents that MongoDB clones on the primary node of the recipient shard during the catch-up phase of the range migration procedure.

For details about data synchronization, see Replica Set Data Synchronization.

Only available on a shard.

Available starting in MongoDB 7.1 (and 7.0, 6.3.2, 6.0.6, and 5.0.18).

shardingStatistics.countBytesClonedOnCatchUpOnRecipient

The cumulative number of bytes that MongoDB clones on the primary node of the recipient shard during the catch-up phase of the range migration procedure.

For details about data synchronization, see Replica Set Data Synchronization.

Only available on a shard.

Available starting in MongoDB 7.1 (and 7.0, 6.3.2, 6.0.6, and 5.0.18).

shardingStatistics.countDocsClonedOnDonor

The cumulative, always-increasing count of documents that MongoDB clones on the primary node of the donor shard.

Only present when run on a shard.

shardingStatistics.countRecipientMoveChunkStarted

Cumulative, always-increasing count of chunks this member, acting as the primary of the recipient shard, has started to receive (whether the move has succeeded or not).

Only present when run on a shard.

shardingStatistics.countDocsDeletedByRangeDeleter

The cumulative, always-increasing count of documents that MongoDB deletes on the primary node of the donor shard during chunk migration.

Only present when run on a shard.

Changed in version 7.1.

shardingStatistics.countDonorMoveChunkLockTimeout

The cumulative, always-increasing count of chunk migrations that MongoDB aborts on the primary node of the donor shard due to lock acquisition timeouts.

Only present when run on a shard.

shardingStatistics.unfinishedMigrationFromPreviousPrimary

The number of unfinished migrations left by the previous primary after an election. This value is only updated after the newly-elected mongod completes the transition to primary.

Only present when run on a shard.

shardingStatistics.chunkMigrationConcurrency

The number of threads on the source shard and the receiving shard for performing chunk migration operations.

Only present when run on a shard.

Available starting in MongoDB 6.3 (and 5.0.15).

shardingStatistics.catalogCache: A document with statistics about the cluster's routing information cache.

shardingStatistics.catalogCache.numDatabaseEntries: The total number of database entries that are currently in the catalog cache.

shardingStatistics.catalogCache.numCollectionEntries: The total number of collection entries (across all databases) that are currently in the catalog cache.

shardingStatistics.catalogCache.countStaleConfigErrors: The total number of times that threads hit stale config exception. A stale config exception triggers a refresh of the metadata.

shardingStatistics.catalogCache.totalRefreshWaitTimeMicros: The cumulative time, in microseconds, that threads had to wait for a refresh of the metadata.

shardingStatistics.catalogCache.numActiveIncrementalRefreshes: The number of incremental catalog cache refreshes that are currently waiting to complete.

shardingStatistics.countIncrementalRefreshesStarted: The cumulative number of incremental refreshes that have started.

shardingStatistics.catalogCache.numActiveFullRefreshes: The number of full catalog cache refreshes that are currently waiting to complete.

shardingStatistics.catalogCache.countFullRefreshesStarted: The cumulative number of full refreshes that have started.

shardingStatistics.catalogCache.countFailedRefreshes: The cumulative number of full or incremental refreshes that have failed.

shardingStatistics.countTransitionToDedicatedConfigServerStarted

Number of times the transitionToDedicatedConfigServer command has started.

Only present when run on a config server node.

New in version 8.0.

shardingStatistics.countTransitionToDedicatedConfigServerCompleted

Number of times the transitionToDedicatedConfigServer command has finished.

Only present when run on a config server node.

New in version 8.0.

shardingStatistics.countTransitionFromDedicatedConfigServerCompleted

Number of times the transitionFromDedicatedConfigServer command has finished.

Only present when run on a config server node.

New in version 8.0.

shardingStatistics.rangeDeleterTasks

The current total of the queued chunk range deletion tasks that are ready to run or are running as part of the range migration procedure.

Inspect the documents in the config.rangeDeletions collection for information about the chunk ranges pending deletion from a shard after a chunk migration.

Only present when run on a shard member.

shardingStatistics.configServerInShardCache: A boolean that indicates whether the config server is a config shard. This value periodically refreshes, so the value of configServerInShardCache might be stale for up to approximately one minute in a healthy cluster. If the node can't communicate with the config server, configServerInShardCache may remain stale for a longer period.

shardingStatistics.resharding

A document with statistics about resharding operations.

Each shard returns its own resharding operation statistics. If a shard is not involved in a resharding operation, then that shard will not contain statistics about the resharding operation.

Only present when run on a shard or config server.

New in version 5.0.

shardingStatistics.resharding.countStarted

The sum of countSucceeded, countFailed, and countCanceled. The sum is further incremented by 1 if a resharding operation has started but has not yet completed. Sum is set to 0 when mongod is started or restarted.

Only present when run on a shard or config server.

New in version 5.0.

shardingStatistics.resharding.countSucceeded

Number of successful resharding operations. Number is set to 0 when mongod is started or restarted.

Only present when run on a shard or config server.

New in version 5.0.

shardingStatistics.resharding.countFailed

Number of failed resharding operations. Number is set to 0 when mongod is started or restarted.

Only present when run on a shard or config server.

New in version 5.0.

shardingStatistics.resharding.countCanceled

Number of canceled resharding operations. Number is set to 0 when mongod is started or restarted.

Only present when run on a shard or config server.

New in version 5.0.

shardingStatistics.resharding.active.documentsCopied

Number of documents copied from donor shards to recipient shards for the current resharding operation. Number is set to 0 when a new resharding operation starts.

Only present when run on a shard or config server. Returns 0 on a config server.

New in version 5.0.

Updated in version 6.1

shardingStatistics.resharding.active.bytesCopied

Number of bytes copied from donor shards to recipient shards for the current resharding operation. Number is set to 0 when a new resharding operation starts.

Only present when run on a shard or config server. Returns 0 on a config server.

New in version 5.0.

Updated in version 6.1

shardingStatistics.resharding.active.countWritesToStashCollections: During resharding, the number of writes to the recipient stash collections.
New in version 6.1.

shardingStatistics.resharding.active.countWritesDuringCriticalSection

Number of writes perfomed in the critical section for the current resharding operation. The critical section prevents new incoming writes to the collection currently being resharded. Number is set to 0 when a new resharding operation starts.

Only present when run on a shard or config server. Returns 0 on a config server.

New in version 5.0.

Updated in version 6.1

shardingStatistics.resharding.active.countReadsDuringCriticalSection: During resharding, the number of reads attempted during the donor's critical section.
New in version 6.1.

shardingStatistics.resharding.active.oplogEntriesFetched

Number of entries fetched from the oplog for the current resharding operation. Number is set to 0 when a new resharding operation starts.

Only present when run on a shard or config server. Returns 0 on a config server.

Updated in version 6.1

shardingStatistics.resharding.active.oplogEntriesApplied

Number of entries applied to the oplog for the current resharding operation. Number is set to 0 when a new resharding operation starts.

Only present when run on a shard or config server. Returns 0 on a config server.

New in version 5.0.

Updated in version 6.1

shardingStatistics.resharding.active.insertsApplied: The total number of insert operations applied during resharding.
New in version 6.1.

shardingStatistics.resharding.active.updatesApplied: The total number of update operations applied during resharding.
New in version 6.1.

shardingStatistics.resharding.active.deletesApplied: The total number of delete operations applied during resharding.
New in version 6.1.

shardingStatistics.resharding.oldestActive.coordinatorAllShardsHighestRemainingOperationTimeEstimatedMillis: Calculated across all shards, the highest estimate of the number of seconds remaining. If the time estimate cannot be computed, the value is set to -1.
New in version 6.1.

shardingStatistics.resharding.oldestActive.coordinatorAllShardsLowestRemainingOperationTimeEstimatedMillis: Calculated across all shards, the lowest estimate of the number of seconds remaining. If the time estimate cannot be computed, the value is set to -1.
New in version 6.1.

shardingStatistics.resharding.oldestActive.recipientRemainingOperationTimeEstimatedMillis

Estimated remaining time, in milliseconds, for the current resharding operation. Prior to resharding, or when the time cannot be calculated, the value is set to -1.

If a shard is involved in multiple resharding operations, this field contains the remaining time estimate for the oldest resharding operation where this shard is a recipient.

New in version 6.1.

shardingStatistics.resharding.oldestActive.totalOperationTimeElapsedMillis

Total elapsed time, in milliseconds, for the current resharding operation. Time is set to 0 when a new resharding operation starts.

Only present when run on a shard or config server. Returns 0 on a config server.

New in version 5.0.

shardingStatistics.resharding.latencies: Timing metrics for resharding operations.
New in version 6.1.

shardingStatistics.resharding.latencies.collectionCloningTotalRemoteBatchRetrievalTimeMillis: Total time recipients spent retrieving batches of documents from donors, in milliseconds.
New in version 6.1.

shardingStatistics.resharding.latencies.collectionCloningTotalRemoteBatchesRetrieved: Total number of batches of documents recipients retrieved from donors.
New in version 6.1.

shardingStatistics.resharding.latencies.collectionCloningTotalLocalInsertTimeMillis: Total time recipients spent inserting batches of documents from donors, in milliseconds.
New in version 6.1.

shardingStatistics.resharding.latencies.collectionCloningTotalLocalInserts: Total number of batches of documents from donors that recipients inserted.
New in version 6.1.

shardingStatistics.resharding.latencies.oplogFetchingTotalRemoteBatchRetrievalTimeMillis: Total time recipients spent retrieving batches of oplog entries from donors, in milliseconds.
New in version 6.1.

shardingStatistics.resharding.latencies.oplogFetchingTotalRemoteBatchesRetrieved: Total number of batches of oplog entries recipients retrieved from donors.
New in version 6.1.

shardingStatistics.resharding.latencies.oplogFetchingTotalLocalInsertTimeMillis: Total time recipients spent inserting batches of oplog entries from donors, in milliseconds.
New in version 6.1.

shardingStatistics.resharding.latencies.oplogFetchingTotalLocalInserts: Total number of batches of oplog entries from donors that recipients inserted.
New in version 6.1.

shardingStatistics.resharding.latencies.oplogApplyingTotalLocalBatchRetrievalTimeMillis: Total time recipients spent retrieving batches of oplog entries that were inserted during fetching, in milliseconds.
New in version 6.1.

shardingStatistics.resharding.latencies.oplogApplyingTotalLocalBatchesRetrieved: Total number of batches of oplog entries that were inserted during fetching that recipients retrieved.
New in version 6.1.

shardingStatistics.resharding.latencies.oplogApplyingTotalLocalBatchApplyTimeMillis: Total time recipients spent applying batches of oplog entries, in milliseconds.
New in version 6.1.

shardingStatistics.resharding.latencies.oplogApplyingTotalLocalBatchesApplied: Total number of batches of oplog entries that recipients applied.
New in version 6.1.

shardingStatistics.resharding.totalApplyTimeElapsedMillis

Total elapsed time, in milliseconds, for the apply step of the current resharding operation. In the apply step, recipient shards modify their data based on new incoming writes from donor shards. Time is set to 0 when a new resharding operation starts.

Only present when run on a shard or config server. Returns 0 on a config server.

New in version 5.0.

shardingStatistics.resharding.totalCriticalSectionTimeElapsedMillis

Total elapsed time, in milliseconds, for the critical section of the current resharding operation. The critical section prevents new incoming writes to the collection currently being resharded. Time is set to 0 when a new resharding operation starts.

Only present when run on a shard or config server. Returns 0 on a config server.

New in version 5.0.

shardingStatistics.resharding.donorState

State of the donor shard for the current resharding operation. Number is set to 0 when a new resharding operation starts.

Number Returned	Meaning	Description
0	`unused`	The shard is not a donor in the current resharding operation.
1	`preparing-to-donate`	The donor shard is preparing to donate data to the recipient shards.
2	`donating-initial-data`	The donor shard is donating data to the recipient shards.
3	`donating-oplog-entries`	The donor shard is donating oplog entries to the recipient shards.
4	`preparing-to-block-writes`	The donor shard is about to prevent new incoming write operations to the collection that is being resharded.
5	`error`	An error occurred during the resharding operation.
6	`blocking-writes`	The donor shard is preventing new incoming write operations and the donor shard has notified all recipient shards that new incoming writes are prevented.
7	`done`	The donor shard has dropped the old sharded collection and the resharding operation is complete.

Only present when run on a shard or config server. Returns 0 on a config server.

New in version 5.0.

shardingStatistics.resharding.recipientState

State of the recipient shard for the current resharding operation. Number is set to 0 when a new resharding operation starts.

Number Returned	Meaning	Description
0	`unused`	Shard is not a recipient in the current resharding operation.
1	`awaiting-fetch-timestamp`	The recipient shard is waiting for the donor shards to be prepared to donate their data
2	`creating-collection`	The recipient shard is creating the new sharded collection.
3	`cloning`	The recipient shard is receiving data from the donor shards.
4	`applying`	The recipient shard is applying oplog entries to modify its copy of the data based on the new incoming writes from donor shards.
5	`error`	An error occurred during the resharding operation.
6	`strict-consistency`	The recipient shard has all data changes stored in a temporary collection.
7	`done`	The resharding operation is complete.

Only present when run on a shard or config server. Returns 0 on a config server.

New in version 5.0.

shardingStatistics.numHostsTargeted

Indicates the number of shards targeted for CRUD operations and aggregation commands. When a CRUD operation or aggregation command is run, the following metrics will be incremented.

Name	Description
`allShards`	A command targeted all shards
`manyShards`	A command targeted more than one shard
`oneShard`	A command targeted one shard
`unsharded`	A command was run on an unsharded collection

Note

Running the serverStatus command on mongos will provide insight into the CRUD and aggregation operations that run on a sharded cluster.

Multi-shard operations can either be scatter-gather or shard specific. Multi-shard scatter-gather operations can consume more resources. By using the shardingStatistics.numHostsTargeted metrics you can tune the aggregation queries that run on a sharded cluster.

shardingStatistics.resharding.coordinatorState

State of the resharding coordinator for the current resharding operation. The resharding coordinator is a thread that runs on the config server primary. Number is set to 0 when a new resharding operation starts.

Number Returned	Meaning	Description
0	`unused`	The shard is not the coordinator in the current resharding operation.
1	`initializing`	The resharding coordinator has inserted the coordinator document into `config.reshardingOperations` and has added the `reshardingFields` to the `config.collections` entry for the original collection.
2	`preparing-to-donate`	The resharding coordinator has created a `config.collections` entry for the temporary resharding collection. has inserted entries into `config.chunks` for ranges based on the new shard key. has inserted entries into `config.tags` for any zones associated with the new shard key. The coordinator informs participant shards to begin the resharding operation. The coordinator then waits until all donor shards have picked a `minFetchTimestamp` and are ready to donate.
3	`cloning`	The resharding coordinator informs donor shards to donate data to recipient shards. The coordinator waits for all recipients to finish cloning the data from the donor.
4	`applying`	The resharding coordinator informs recipient shards to modify their copies of data based on new incoming writes from donor shards. The coordinator waits for all recipients to finish applying oplog entries.
5	`blocking-writes`	The resharding coordinator informs donor shards to prevent new incoming write operations to the collection being resharded. The coordinator then waits for all recipients to have all data changes.
6	`aborting`	An unrecoverable error occurred during the resharding operation or the `abortReshardCollection` command (or the `sh.abortReshardCollection()` method) was run.
6	`committing`	The resharding coordinator removes the `config.collections` entry for the temporary resharding collection. The coordinator then adds the `recipientFields` to the source collection's entry.

Only present when run on a shard or config server.

New in version 5.0.

shardingStatistics.resharding.opStatus

Status for the current resharding operation.

Number Returned	Description
-1	Resharding operation not in progress.
0	Resharding operation succeeded.
1	Resharding operation failed.
2	Resharding operation canceled.

Only present when run on a shard or config server.

New in version 5.0.

shardingStatistics.resharding.lastOpEndingChunkImbalance

This field contains the highest numeric difference for (maxNumChunksInShard - minNumChunksInShard) among all zones for the collection that was processed by the most recent resharding operation.

See Range Size.

Only updated on config servers.

New in version 5.0.

shardedIndexConsistency

shardedIndexConsistency : {
   numShardedCollectionsWithInconsistentIndexes : Long("<num>")
},

shardedIndexConsistency

Available only on config server instances.

A document that returns results of index consistency checks for sharded collections.

The returned metrics are meaningful only when run on the primary of the config server replica set for a sharded cluster.

Tip

enableShardedIndexConsistencyCheck parameter
shardedIndexConsistencyCheckIntervalMS parameter

shardedIndexConsistency.numShardedCollectionsWithInconsistentIndexes

Available only on config server instances.

Number of sharded collections whose indexes are inconsistent across the shards. A sharded collection has an inconsistent index if the collection does not have the exact same indexes (including the index options) on each shard that contains chunks for the collection.

To investigate if a sharded collection has inconsistent indexes, see Find Inconsistent Indexes Across Shards.

The returned metrics are meaningful only when run on the primary of the config server replica set for a sharded cluster.

Tip

enableShardedIndexConsistencyCheck parameter
shardedIndexConsistencyCheckIntervalMS parameter

spillWiredTiger

spillWiredTiger: {
  storageSize: <long>,
  uri: <string>,
  version: <string>,
  'block-manager': {
    'blocks read': <num>,
    'blocks written': <num>,
    'bytes read': <num>,
    'bytes written': <num>
  },
  cache: {
    'application thread time evicting (usecs)': <num>,
    'application threads eviction requested with cache fill ratio < 25%': <num>,
    'application threads eviction requested with cache fill ratio >= 75%': <num>,
    'application threads page write from cache to disk count': <num>,
    'application threads page write from cache to disk time (usecs)': <num>,
    'bytes allocated for updates': <num>,
    'bytes currently in the cache': <num>,
    'bytes read into cache': <num>,
    'bytes written from cache': <num>,
    'eviction currently operating in aggressive mode': <num>,
    'eviction empty score': <num>,
    'eviction state': <num>,
    'eviction walk target strategy clean pages': <num>,
    'eviction walk target strategy dirty pages': <num>,
    'eviction walk target strategy pages with updates': <num>,
    'forced eviction - pages evicted that were clean count': <num>,
    'forced eviction - pages evicted that were dirty count': <num>,
    'forced eviction - pages selected count': <num>,
    'forced eviction - pages selected unable to be evicted count': <num>,
    'hazard pointer blocked page eviction': <num>,
    'maximum bytes configured': <num>,
    'maximum page size seen at eviction': <num>,
    'number of times dirty trigger was reached': <num>,
    'number of times eviction trigger was reached': <num>,
    'number of times updates trigger was reached': <num>,
    'page evict attempts by application threads': <num>,
    'page evict failures by application threads': <num>,
    'pages queued for eviction': <num>,
    'pages queued for urgent eviction': <num>,
    'tracked dirty bytes in the cache': <num>
  }
}

spillWiredTiger

A document that contains metrics on the WiredTiger spill instance. When MongoDB writes to disk to fulfill certain operations, it utilizes a separate WiredTiger instance, which contains its own in-memory cache. This separate cache isolates operations from the main WiredTiger cache.

The spillWiredTiger document contains a subset of the fields reported in the wiredTiger document. The spillWiredTiger document only appears when using the WiredTiger storage engine. For details on the spillWiredTiger metrics, see the corresponding wiredTiger metric description.

storageEngine

storageEngine : {
   name : <string>,
   supportsCommittedReads : <boolean>,
   persistent : <boolean>
},

storageEngine: A document with data about the current storage engine.

storageEngine.name: The name of the current storage engine.

storageEngine.supportsCommittedReads: A boolean that indicates whether the storage engine supports "majority" read concern.

storageEngine.persistent: A boolean that indicates whether the storage engine does or does not persist data to disk.

tcmalloc

Note

tcmalloc metrics that are only for internal use are omitted from this page.

tcmalloc : {
   usingPerCPUCaches : <boolean>,  // Added in MongoDB 8.0
   maxPerCPUCacheSizeBytes : <integer>, // Added in MongoDB 8.0
   generic : {
      current_allocated_bytes : <integer>,
      heap_size : <integer>,
      peak_memory_usage : <integer>  // Added in MongoDB 8.0
   },
   tcmalloc : {
      central_cache_free : <integer>,
      cpu_free : <integer>,  // Added in MongoDB 8.0
      release_rate : <integer>,
      total_bytes_held : <integer>,  // Added in MongoDB 8.0
      cpuCache : {
         0 : {
            overflows : <integer>,  // Added in MongoDB 8.0
            underflows : <integer>  // Added in MongoDB 8.0
         },
      }
   },
   tcmalloc_derived : {
      total_free_bytes : <integer>  // Added in MongoDB 8.0
   }
}

tcmalloc

Note

Starting in version 8.0, MongoDB uses an updated version of TCMalloc that improves memory fragmentation and management. See tcmalloc upgrade for more information.

A document that contains information on memory allocation for the server. By default, tcmalloc metrics are included in the serverStatus output. To change the verbosity of the tcmalloc section, specify an integer between 0 and 3 (inclusive):

If you set verbosity to 0, tcmalloc metrics aren't included in the serverStatus output.
If you set verbosity to 1, the serverStatus output includes the default tcmalloc metrics.
If you set verbosity to 2, the serverStatus output includes default tcmalloc metrics and the tcmalloc.tcmalloc.cpuCache section.
If you set verbosity to 3, the serverStatus output includes all tcmalloc metrics.

If you specify a value higher than 3, MongoDB sets the verbosity to 3.

For example, to call serverStatus with verbosity set to 2, run the following command:

db.runCommand( { serverStatus: 1, tcmalloc: 2 } )

Tip

TCMalloc Stats

tcmalloc.usingPerCPUCaches

A boolean that indicates whether TCMalloc is running with per-CPU caches. If tcmalloc.usingPerCPUCaches is false, ensure that:

You disabled glibc rseq.
You're using Linux kernel version 4.18 or later.

New in version 8.0.

tcmalloc.maxPerCPUCacheSizeBytes: Maximum size, in bytes, of each CPU cache.
New in version 8.0.

tcmalloc.generic.peak_memory_usage: Total amount of memory, in bytes, allocated by MongoDB and sampled by TCMalloc.
New in version 8.0.

tcmalloc.generic.current_allocated_bytes: Total number of bytes that are currently allocated to memory and actively used by MongoDB.

tcmalloc.generic.heap_size: Amount of memory, in bytes, allocated from the operating system. This value includes memory that's currently in use and memory that's been allocated but isn't in use.

tcmalloc.tcmalloc.central_cache_free: Amount of memory, in bytes, held in the central free list. The central free list is a structure that manages free memory for reuse.

tcmalloc.tcmalloc.cpu_free: Amount of free memory, in bytes, available across all CPU caches.
New in version 8.0.

tcmalloc.tcmalloc.total_bytes_held: Amount of memory, in bytes, currently held in caches.
New in version 8.0.

tcmalloc.tcmalloc.release_rate: Rate, in bytes per second, at which unused memory is released to the operating system. The tcmallocReleaseRate parameter determines the value of tcmalloc.tcmalloc.release_rate.

tcmalloc.tcmalloc.cpuCache

A document that provides data on each CPU cache.

cpuCache metrics are excluded at the default verbosity level. To view cpuCache metrics, you must set the tcmalloc verbosity to at least 2.

New in version 8.0.

tcmalloc.tcmalloc.cpuCache.N.overflows: Number of overflows that the CPU cache experienced. Overflows occur when a user deallocates memory and the cache is full.
New in version 8.0.

tcmalloc.tcmalloc.cpuCache.N.underflows: Number of underflows that the CPU cache experienced. Underflows occur when a user allocates memory and the cache is empty.
New in version 8.0.

tcmalloc.tcmalloc_derived.total_free_bytes: Amount of memory remaining before tcmalloc has to request for more memory from the operating system.
New in version 8.0.

transactions

transactions : {
   retriedCommandsCount : Long("<num>"),
   retriedStatementsCount : Long("<num>"),
   transactionsCollectionWriteCount : Long("<num>"),
   currentActive : Long("<num>"),
   currentInactive : Long("<num>"),
   currentOpen : Long("<num>"),
   totalAborted : Long("<num>"),
   totalCommitted : Long("<num>"),
   totalStarted : Long("<num>"),
   totalPrepared : Long("<num>"),
   totalPreparedThenCommitted : Long("<num>"),
   totalPreparedThenAborted :  Long("<num>"),
   currentPrepared :  Long("<num>"),
   lastCommittedTransaction : <document>
},

transactions : {
   currentOpen : Long("<num>"),
   currentActive : Long("<num>"),
   currentInactive : Long("<num>"),
   totalStarted : Long("<num>"),
   totalCommitted : Long("<num>"),
   totalAborted : Long("<num>"),
   abortCause : {
      <String1> : Long("<num>"),
      <String2> : Long("<num>"),
      ...
   },
   totalContactedParticipants : Long("<num>"),
   totalParticipantsAtCommit : Long("<num>"),
   totalRequestsTargeted : Long("<num>"),
   commitTypes : {
      noShards : {
         initiated : Long("<num>"),
         successful : Long("<num>"),
         successfulDurationMicros : Long("<num>")
      },
      singleShard : {
         initiated : Long("<num>"),
         successful : Long("<num>"),
         successfulDurationMicros : Long("<num>")
      },
      singleWriteShard : {
         initiated : Long("<num>"),
         successful : Long("<num>"),
         successfulDurationMicros : Long("<num>")
      },
      readOnly : {
         initiated : Long("<num>"),
         successful : Long("<num>"),
         successfulDurationMicros : Long("<num>")
      },
      twoPhaseCommit : {
         initiated : Long("<num>"),
         successful : Long("<num>"),
         successfulDurationMicros : Long("<num>")
      },
      recoverWithToken : {
         initiated : Long("<num>"),
         successful : Long("<num>"),
         successfulDurationMicros : Long("<num>")
      }
   }
},

transactions

When run on a mongod, a document with data about the retryable writes and transactions.

When run on a mongos, a document with data about the transactions run on the instance.

transactions.retriedCommandsCount

Available on mongod only.

The total number of retry attempts that have been received after the corresponding retryable write command has already been committed. That is, a retryable write is attempted even though the write has previously succeeded and has an associated record for the transaction and session in the config.transactions collection, such as when the initial write response to the client is lost.

Note

MongoDB does not re-execute the committed writes.

The total is across all sessions.

The total does not include any retryable writes that may happen internally as part of a chunk migration.

transactions.retriedStatementsCount

Available on mongod only.

The total number of write statements associated with the retried commands in transactions.retriedCommandsCount.

Note

MongoDB does not re-execute the committed writes.

The total does not include any retryable writes that may happen internally as part of a chunk migration.

transactions.transactionsCollectionWriteCount

Available on mongod only.

The total number of writes to the config.transactions collection, triggered when a new retryable write statement is committed.

For update and delete commands, since only single document operations are retryable, there is one write per statement.

For insert operations, there is one write per batch of documents inserted, except when a failure leads to each document being inserted separately.

The total includes writes to a server's config.transactions collection that occur as part of a migration.

transactions.currentActive

Available on both mongod and mongos.

The total number of open transactions currently executing a command.

transactions.currentInactive

Available on both mongod and mongos.

The total number of open transactions that are not currently executing a command.

transactions.currentOpen

Available on both mongod and mongos.

The total number of open transactions. A transaction is opened when the first command is run as a part of that transaction, and stays open until the transaction either commits or aborts.

transactions.totalAborted

For the mongod, the total number of transactions aborted on this instance since its last startup.

For the mongos, the total number of transactions aborted through this instance since its last startup.

transactions.totalCommitted

For the mongod, the total number of transactions committed on the instance since its last startup.

For the mongos,the total number of transactions committed through this instance since its last startup.

transactions.totalStarted

For the mongod, the total number of transactions started on this instance since its last startup.

For the mongos, the total number of transactions started on this instance since its last startup.

transactions.abortCause

Available on mongos only.

Breakdown of the transactions.totalAborted by cause. If a client issues an explicit abortTransaction, the cause is listed as abort.

For example:

totalAborted : Long("5"),
abortCause : {
   abort : Long("1"),
   DuplicateKey : Long("1"),
   StaleConfig : Long("3"),
   SnapshotTooOld : Long("1")
},

transactions.totalContactedParticipants

Available on mongos only.

The total number of shards contacted for all transactions started through this mongos since its last startup.

The number of shards contacted during the transaction processes can include those shards that may not be included as part of the commit.

transactions.totalParticipantsAtCommit

Available on mongos only.

Total number of shards involved in the commit for all transactions started through this mongos since its last startup.

transactions.totalRequestsTargeted

Available on mongos only.

Total number of network requests targeted by the mongos as part of its transactions.

transactions.commitTypes

Available on mongos only.

Breakdown of the commits by types. For example:

noShards : {
   initiated : Long("0"),
   successful : Long("0"),
   successfulDurationMicros : Long("0")
},
singleShard : {
   initiated : Long("5"),
   successful : Long("5"),
   successfulDurationMicros : Long("203118")
},
singleWriteShard : {
   initiated : Long("0"),
   successful : Long("0"),
   successfulDurationMicros : Long("0")
},
readOnly : {
   initiated : Long("0"),
   successful : Long("0"),
   successfulDurationMicros : Long("0")
},
twoPhaseCommit : {
   initiated : Long("1"),
   successful : Long("1"),
   successfulDurationMicros : Long("179616")
},
recoverWithToken : {
   initiated : Long("0"),
   successful : Long("0"),
   successfulDurationMicros : Long("0")
}

The types of commit are:

Type	Description
`noShards`	Commits of transactions that did not contact any shards.
`singleShard`	Commits of transactions that affected a single shard.
`singleWriteShard`	Commits of transactions that contacted multiple shards but whose write operations only affected a single shard.
`readOnly`	Commits of transactions that only involved read operations.
`twoPhaseCommit`	Commits of transactions that included writes to multiple shards
`recoverWithToken`	Commits that recovered the outcome of transactions from another instance or after this instance was restarted.

For each commit type, the command returns the following metrics:

Metrics	Description
`initiated`	Total number of times that commits of this type were initiated.
`successful`	Total number of times that commits of this type succeeded.
`successfulDurationMicros`	Total time, in microseconds, taken by successful commits of this type.

transactions.totalPrepared

Available on mongod only.

The total number of transactions in prepared state on this server since the mongod process's last startup.

transactions.totalPreparedThenCommitted

Available on mongod only.

The total number of transactions that were prepared and committed on this server since the mongod process's last startup.

transactions.totalPreparedThenAborted

Available on mongod only.

The total number of transactions that were prepared and aborted on this server since the mongod process's last startup.

transactions.currentPrepared

Available on mongod only.

The current number of transactions in prepared state on this server.

transactions.lastCommittedTransaction

Available on mongod only.

The details of the last transaction committed when the mongod is primary.

When returned from a secondary, lastCommittedTransaction returns the details of the last transaction committed when that secondary was a primary.

lastCommittedTransaction : {
   operationCount : Long("1"),
   oplogOperationBytes : Long("211"),
   writeConcern : {
      w : "majority",
      wtimeout : 0
   }
}

Metrics	Description
`operationCount`	The number of write operations in the transaction.
`oplogOperationBytes`	The size of the corresponding oplog entry or entries for the transaction. [2]
`writeConcern`	The write concern used for the transaction.

[2]	MongoDB creates as many oplog entries as necessary to encapsulate all write operations in a transaction. See Oplog Size Limit for details.

transportSecurity

transportSecurity : {
   1.0 : Long("<num>"),
   1.1 : Long("<num>"),
   1.2 : Long("<num>"),
   1.3 : Long("<num>"),
   unknown : Long("<num>")
},

transportSecurity.<version>: The cumulative number of TLS <version> connections that have been made to this mongod or mongos instance. The value is reset upon restart.

watchdog

watchdog : {
   checkGeneration : Long("<num>"),
   monitorGeneration : Long("<num>"),
   monitorPeriod : <num>
}

Note

The watchdog section is only present if the Storage Node Watchdog is enabled.

watchdog: A document reporting the status of the Storage Node Watchdog.

watchdog.checkGeneration: The number of times the directories have been checked since startup. Directories are checked multiple times every monitoringPeriod.

watchdog.monitorGeneration: The number of times the status of all filesystems used by mongod has been examined. This is incremented once every monitoringPeriod.

watchdog.monitorPeriod: The value set by watchdogPeriodSeconds. This is the period between status checks.

wiredTiger

wiredTiger information only appears if using the WiredTiger storage engine. Some of the statistics roll up for the server.

{
   uri : 'statistics:',
   version: <string>,
   async : {
      current work queue length : <num>,
      maximum work queue length : <num>,
      number of allocation state races : <num>,
      number of flush calls : <num>,
      number of operation slots viewed for allocation : <num>,
      number of times operation allocation failed : <num>,
      number of times worker found no work : <num>,
      total allocations : <num>,
      total compact calls : <num>,
      total insert calls : <num>,
      total remove calls : <num>,
      total search calls : <num>,
      total update calls : <num>
   },
   block-manager : {
      blocks pre-loaded : <num>,
      blocks read : <num>,
      blocks written : <num>,
      bytes read : <num>,
      bytes written : <num>,
      bytes written for checkpoint : <num>,
      mapped blocks read : <num>,
      mapped bytes read : <num>
   },
   cache : {
      application threads page read from disk to cache count : <num>,
      application threads page read from disk to cache time (usecs) : <num>,
      application threads page write from cache to disk count : <num>,
      application threads page write from cache to disk time (usecs) : <num>,
      bytes belonging to page images in the cache : <num>,
      bytes belonging to the cache overflow table in the cache : <num>,
      bytes currently in the cache : <num>,
      bytes dirty in the cache cumulative : <num>,
      bytes not belonging to page images in the cache : <num>,
      bytes read into cache : <num>,
      bytes written from cache : <num>,
      cache overflow cursor application thread wait time (usecs) : <num>,
      cache overflow cursor internal thread wait time (usecs) : <num>,
      cache overflow score : <num>,
      cache overflow table entries : <num>,
      cache overflow table insert calls : <num>,
      cache overflow table max on-disk size : <num>,
      cache overflow table on-disk size : <num>,
      cache overflow table remove calls : <num>,
      checkpoint blocked page eviction : <num>,
      eviction calls to get a page : <num>,
      eviction calls to get a page found queue empty : <num>,
      eviction calls to get a page found queue empty after locking : <num>,
      eviction currently operating in aggressive mode : <num>,
      eviction empty score : <num>,
      eviction passes of a file : <num>,
      eviction server candidate queue empty when topping up : <num>,
      eviction server candidate queue not empty when topping up : <num>,
      eviction server evicting pages : <num>,
      eviction server slept, because we did not make progress with eviction : <num>,
      eviction server unable to reach eviction goal : <num>,
      eviction server waiting for a leaf page : <num>,
      eviction server waiting for an internal page sleep (usec) : <num>,
      eviction server waiting for an internal page yields : <num>,
      eviction state : <num>,
      eviction walk target pages histogram - 0-9 : <num>,
      eviction walk target pages histogram - 10-31 : <num>,
      eviction walk target pages histogram - 128 and higher : <num>,
      eviction walk target pages histogram - 32-63 : <num>,
      eviction walk target pages histogram - 64-128 : <num>,
      eviction walks abandoned : <num>,
      eviction walks gave up because they restarted their walk twice : <num>,
      eviction walks gave up because they saw too many pages and found no candidates : <num>,
      eviction walks gave up because they saw too many pages and found too few candidates : <num>,
      eviction walks reached end of tree : <num>,
      eviction walks started from root of tree : <num>,
      eviction walks started from saved location in tree : <num>,
      eviction worker thread active : <num>,
      eviction worker thread created : <num>,
      eviction worker thread evicting pages : <num>,
      eviction worker thread removed : <num>,
      eviction worker thread stable number : <num>,
      files with active eviction walks : <num>,
      files with new eviction walks started : <num>,
      force re-tuning of eviction workers once in a while : <num>,
      forced eviction - pages evicted that were clean count : <num>,
      forced eviction - pages evicted that were clean time (usecs) : <num>,
      forced eviction - pages evicted that were dirty count : <num>,
      forced eviction - pages evicted that were dirty time (usecs) : <num>,
      forced eviction - pages selected because of too many deleted items count : <num>,
      forced eviction - pages selected count : <num>,
      forced eviction - pages selected unable to be evicted count : <num>,
      forced eviction - pages selected unable to be evicted time : <num>,
      hazard pointer blocked page eviction : <num>,
      hazard pointer check calls : <num>,
      hazard pointer check entries walked : <num>,
      hazard pointer maximum array length : <num>,
      in-memory page passed criteria to be split : <num>,
      in-memory page splits : <num>,
      internal pages evicted : <num>,
      internal pages split during eviction : <num>,
      leaf pages split during eviction : <num>,
      maximum bytes configured : <num>,
      maximum page size at eviction : <num>,
      modified pages evicted : <num>,
      modified pages evicted by application threads : <num>,
      operations timed out waiting for space in cache : <num>,
      overflow pages read into cache : <num>,
      page split during eviction deepened the tree : <num>,
      page written requiring cache overflow records : <num>,
      pages currently held in the cache : <num>,
      pages evicted by application threads : <num>,
      pages queued for eviction : <num>,
      pages queued for eviction post lru sorting : <num>,
      pages queued for urgent eviction : <num>,
      pages queued for urgent eviction during walk : <num>,
      pages read into cache : <num>,
      pages read into cache after truncate : <num>,
      pages read into cache after truncate in prepare state : <num>,
      pages read into cache requiring cache overflow entries : <num>,
      pages read into cache requiring cache overflow for checkpoint : <num>,
      pages read into cache skipping older cache overflow entries : <num>,
      pages read into cache with skipped cache overflow entries needed later : <num>,
      pages read into cache with skipped cache overflow entries needed later by checkpoint : <num>,
      pages requested from the cache : <num>,
      pages seen by eviction walk : <num>,
      pages selected for eviction unable to be evicted : <num>,
      pages walked for eviction : <num>,
      pages written from cache : <num>,
      pages written requiring in-memory restoration : <num>,
      percentage overhead : <num>,
      tracked bytes belonging to internal pages in the cache : <num>,
      tracked bytes belonging to leaf pages in the cache : <num>,
      tracked dirty bytes in the cache : <num>,
      tracked dirty pages in the cache : <num>,
      unmodified pages evicted : <num>
   },
   capacity : {
      background fsync file handles considered : <num>,
      background fsync file handles synced : <num>,
      background fsync time (msecs) : <num>,
      bytes read : <num>,
      bytes written for checkpoint : <num>,
      bytes written for eviction : <num>,
      bytes written for log : <num>,
      bytes written total : <num>,
      threshold to call fsync : <num>,
      time waiting due to total capacity (usecs) : <num>,
      time waiting during checkpoint (usecs) : <num>,
      time waiting during eviction (usecs) : <num>,
      time waiting during logging (usecs) : <num>,
      time waiting during read (usecs) : <num>
   },
   connection : {
      auto adjusting condition resets : <num>,
      auto adjusting condition wait calls : <num>,
      detected system time went backwards : <num>,
      files currently open : <num>,
      memory allocations : <num>,
      memory frees : <num>,
      memory re-allocations : <num>,
      pthread mutex condition wait calls : <num>,
      pthread mutex shared lock read-lock calls : <num>,
      pthread mutex shared lock write-lock calls : <num>,
      total fsync I/Os : <num>,
      total read I/Os : <num>,
      total write I/Os : <num>
   },
   cursor : {
      cached cursor count : <num>,
      cursor bulk loaded cursor insert calls : <num>,
      cursor close calls that result in cache : <num>,
      cursor create calls : <num>,
      cursor insert calls : <num>,
      cursor insert key and value bytes : <num>,
      cursor modify calls : <num>,
      cursor modify key and value bytes affected : <num>,
      cursor modify value bytes modified : <num>,
      cursor next calls : <num>,
      cursor operation restarted : <num>,
      cursor prev calls : <num>,
      cursor remove calls : <num>,
      cursor remove key bytes removed : <num>,
      cursor reserve calls : <num>,
      cursor reset calls : <num>,
      cursor search calls : <num>,
      cursor search near calls : <num>,
      cursor sweep buckets : <num>,
      cursor sweep cursors closed : <num>,
      cursor sweep cursors examined : <num>,
      cursor sweeps : <num>,
      cursor truncate calls : <num>,
      cursor update calls : <num>,
      cursor update key and value bytes : <num>,
      cursor update value size change : <num>,
      cursors reused from cache : <num>,
      open cursor count : <num>
   },
   data-handle : {
      connection data handle size : <num>,
      connection data handles currently active : <num>,
      connection sweep candidate became referenced : <num>,
      connection sweep dhandles closed : <num>,
      connection sweep dhandles removed from hash list : <num>,
      connection sweep time-of-death sets : <num>,
      connection sweeps : <num>,
      session dhandles swept : <num>,
      session sweep attempts : <num>
   },
   lock : {
      checkpoint lock acquisitions : <num>,
      checkpoint lock application thread wait time (usecs) : <num>,
      checkpoint lock internal thread wait time (usecs) : <num>,
      dhandle lock application thread time waiting (usecs) : <num>,
      dhandle lock internal thread time waiting (usecs) : <num>,
      dhandle read lock acquisitions : <num>,
      dhandle write lock acquisitions : <num>,
      durable timestamp queue lock application thread time waiting (usecs) : <num>,
      durable timestamp queue lock internal thread time waiting (usecs) : <num>,
      durable timestamp queue read lock acquisitions : <num>,
      durable timestamp queue write lock acquisitions : <num>,
      metadata lock acquisitions : <num>,
      metadata lock application thread wait time (usecs) : <num>,
      metadata lock internal thread wait time (usecs) : <num>,
      read timestamp queue lock application thread time waiting (usecs) : <num>,
      read timestamp queue lock internal thread time waiting (usecs) : <num>,
      read timestamp queue read lock acquisitions : <num>,
      read timestamp queue write lock acquisitions : <num>,
      schema lock acquisitions : <num>,
      schema lock application thread wait time (usecs) : <num>,
      schema lock internal thread wait time (usecs) : <num>,
      table lock application thread time waiting for the table lock (usecs) : <num>,
      table lock internal thread time waiting for the table lock (usecs) : <num>,
      table read lock acquisitions : <num>,
      table write lock acquisitions : <num>,
      txn global lock application thread time waiting (usecs) : <num>,
      txn global lock internal thread time waiting (usecs) : <num>,
      txn global read lock acquisitions : <num>,
      txn global write lock acquisitions : <num>
   },
   log : {
      busy returns attempting to switch slots : <num>,
      force archive time sleeping (usecs) : <num>,
      log bytes of payload data : <num>,
      log bytes written : <num>,
      log files manually zero-filled : <num>,
      log flush operations : <num>,
      log force write operations : <num>,
      log force write operations skipped : <num>,
      log records compressed : <num>,
      log records not compressed : <num>,
      log records too small to compress : <num>,
      log release advances write LSN : <num>,
      log scan operations : <num>,
      log scan records requiring two reads : <num>,
      log server thread advances write LSN : <num>,
      log server thread write LSN walk skipped : <num>,
      log sync operations : <num>,
      log sync time duration (usecs) : <num>,
      log sync_dir operations : <num>,
      log sync_dir time duration (usecs) : <num>,
      log write operations : <num>,
      logging bytes consolidated : <num>,
      maximum log file size : <num>,
      number of pre-allocated log files to create : <num>,
      pre-allocated log files not ready and missed : <num>,
      pre-allocated log files prepared : <num>,
      pre-allocated log files used : <num>,
      records processed by log scan : <num>,
      slot close lost race : <num>,
      slot close unbuffered waits : <num>,
      slot closures : <num>,
      slot join atomic update races : <num>,
      slot join calls atomic updates raced : <num>,
      slot join calls did not yield : <num>,
      slot join calls found active slot closed : <num>,
      slot join calls slept : <num>,
      slot join calls yielded : <num>,
      slot join found active slot closed : <num>,
      slot joins yield time (usecs) : <num>,
      slot transitions unable to find free slot : <num>,
      slot unbuffered writes : <num>,
      total in-memory size of compressed records : <num>,
      total log buffer size : <num>,
      total size of compressed records : <num>,
      written slots coalesced : <num>,
      yields waiting for previous log file close : <num>
   },
   perf : {
      file system read latency histogram (bucket 1) - 10-49ms : <num>,
      file system read latency histogram (bucket 2) - 50-99ms : <num>,
      file system read latency histogram (bucket 3) - 100-249ms : <num>,
      file system read latency histogram (bucket 4) - 250-499ms : <num>,
      file system read latency histogram (bucket 5) - 500-999ms : <num>,
      file system read latency histogram (bucket 6) - 1000ms+ : <num>,
      file system write latency histogram (bucket 1) - 10-49ms : <num>,
      file system write latency histogram (bucket 2) - 50-99ms : <num>,
      file system write latency histogram (bucket 3) - 100-249ms : <num>,
      file system write latency histogram (bucket 4) - 250-499ms : <num>,
      file system write latency histogram (bucket 5) - 500-999ms : <num>,
      file system write latency histogram (bucket 6) - 1000ms+ : <num>,
      operation read latency histogram (bucket 1) - 100-249us : <num>,
      operation read latency histogram (bucket 2) - 250-499us : <num>,
      operation read latency histogram (bucket 3) - 500-999us : <num>,
      operation read latency histogram (bucket 4) - 1000-9999us : <num>,
      operation read latency histogram (bucket 5) - 10000us+ : <num>,
      operation write latency histogram (bucket 1) - 100-249us : <num>,
      operation write latency histogram (bucket 2) - 250-499us : <num>,
      operation write latency histogram (bucket 3) - 500-999us : <num>,
      operation write latency histogram (bucket 4) - 1000-9999us : <num>,
      operation write latency histogram (bucket 5) - 10000us+ : <num>
   },
   reconciliation : {
      fast-path pages deleted : <num>,
      page reconciliation calls : <num>,
      page reconciliation calls for eviction : <num>,
      pages deleted : <num>,
      split bytes currently awaiting free : <num>,
      split objects currently awaiting free : <num>
   },
   session : {
      open session count : <num>,
      session query timestamp calls : <num>,
      table alter failed calls : <num>,
      table alter successful calls : <num>,
      table alter unchanged and skipped : <num>,
      table compact failed calls : <num>,
      table compact successful calls : <num>,
      table create failed calls : <num>,
      table create successful calls : <num>,
      table drop failed calls : <num>,
      table drop successful calls : <num>,
      table import failed calls : <num>,
      table import successful calls : <num>,
      table rebalance failed calls : <num>,
      table rebalance successful calls : <num>,
      table rename failed calls : <num>,
      table rename successful calls : <num>,
      table salvage failed calls : <num>,
      table salvage successful calls : <num>,
      table truncate failed calls : <num>,
      table truncate successful calls : <num>,
      table verify failed calls : <num>,
      table verify successful calls : <num>
   },
   thread-state : {
      active filesystem fsync calls : <num>,
      active filesystem read calls : <num>,
      active filesystem write calls : <num>
   },
   thread-yield : {
      application thread time evicting (usecs) : <num>,
      application thread time waiting for cache (usecs) : <num>,
      connection close blocked waiting for transaction state stabilization : <num>,
      connection close yielded for lsm manager shutdown : <num>,
      data handle lock yielded : <num>,
      get reference for page index and slot time sleeping (usecs) : <num>,
      log server sync yielded for log write : <num>,
      page access yielded due to prepare state change : <num>,
      page acquire busy blocked : <num>,
      page acquire eviction blocked : <num>,
      page acquire locked blocked : <num>,
      page acquire read blocked : <num>,
      page acquire time sleeping (usecs) : <num>,
      page delete rollback time sleeping for state change (usecs) : <num>,
      page reconciliation yielded due to child modification : <num>
   },
   transaction : {
      Number of prepared updates : <num>,
      Number of prepared updates added to cache overflow : <num>,
      Number of prepared updates resolved : <num>,
      durable timestamp queue entries walked : <num>,
      durable timestamp queue insert to empty : <num>,
      durable timestamp queue inserts to head : <num>,
      durable timestamp queue inserts total : <num>,
      durable timestamp queue length : <num>,
      number of named snapshots created : <num>,
      number of named snapshots dropped : <num>,
      prepared transactions : <num>,
      prepared transactions committed : <num>,
      prepared transactions currently active : <num>,
      prepared transactions rolled back : <num>,
      query timestamp calls : <num>,
      read timestamp queue entries walked : <num>,
      read timestamp queue insert to empty : <num>,
      read timestamp queue inserts to head : <num>,
      read timestamp queue inserts total : <num>,
      read timestamp queue length : <num>,
      rollback to stable calls : <num>,
      rollback to stable updates aborted : <num>,
      rollback to stable updates removed from cache overflow : <num>,
      set timestamp calls : <num>,
      set timestamp durable calls : <num>,
      set timestamp durable updates : <num>,
      set timestamp oldest calls : <num>,
      set timestamp oldest updates : <num>,
      set timestamp stable calls : <num>,
      set timestamp stable updates : <num>,
      transaction begins : <num>,
      transaction checkpoint currently running : <num>,
      transaction checkpoint generation : <num>,
      transaction checkpoint max time (msecs) : <num>,
      transaction checkpoint min time (msecs) : <num>,
      transaction checkpoint most recent time (msecs) : <num>,
      transaction checkpoint scrub dirty target : <num>,
      transaction checkpoint scrub time (msecs) : <num>,
      transaction checkpoint total time (msecs) : <num>,
      transaction checkpoints : <num>,
      transaction checkpoints skipped because database was clean : <num>,
      transaction failures due to cache overflow : <num>,
      transaction fsync calls for checkpoint after allocating the transaction ID : <num>,
      transaction fsync duration for checkpoint after allocating the transaction ID (usecs) : <num>,
      transaction range of IDs currently pinned : <num>,
      transaction range of IDs currently pinned by a checkpoint : <num>,
      transaction range of IDs currently pinned by named snapshots : <num>,
      transaction range of timestamps currently pinned : <num>,
      transaction range of timestamps pinned by a checkpoint : <num>,
      transaction range of timestamps pinned by the oldest active read timestamp : <num>,
      transaction range of timestamps pinned by the oldest timestamp : <num>,
      transaction read timestamp of the oldest active reader : <num>,
      transaction sync calls : <num>,
      transactions committed : <num>,
      transactions rolled back : <num>,
      update conflicts : <num>
   },
   concurrentTransactions : {
      write : {
         out : <num>,
         available : <num>,
         totalTickets : <num>
      },
      read : {
         out : <num>,
         available : <num>,
         totalTickets : <num>
      },
      monitor : {
         timesDecreased: <num>,
         timesIncreased: <num>,
         totalAmountDecreased: <num>,
         totalAmountIncreased: <num>
      }
   },
   snapshot-window-settings : {
      total number of SnapshotTooOld errors : <num>,
      max target available snapshots window size in seconds : <num>,
      target available snapshots window size in seconds : <num>,
      current available snapshots window size in seconds : <num>,
      latest majority snapshot timestamp available : <string>,
      oldest majority snapshot timestamp available : <string>
   }
}

Note

The following is not an exhaustive list.

wiredTiger.uri: A string. For internal use by MongoDB.

wiredTiger.version: A string that returns the WiredTiger storage engine version.
New in version 8.1.

wiredTiger.async: A document that returns statistics related to the asynchronous operations API. This is unused by MongoDB.

wiredTiger.block-manager: A document that returns statistics on the block manager operations.

wiredTiger.cache

A document that returns statistics on the cache and page evictions from the cache.

The following describes some of the key wiredTiger.cache statistics:

wiredTiger.cache.maximum bytes configured: Maximum cache size.

wiredTiger.cache.bytes currently in the cache: Size in bytes of the data currently in cache. This value should not be greater than the maximum bytes configured value.

wiredTiger.cache.unmodified pages evicted: Main statistics for page eviction.

wiredTiger.cache.tracked dirty bytes in the cache: Size in bytes of the dirty data in the cache. This value should be less than the bytes currently in the cache value.

wiredTiger.cache.pages read into cache: Number of pages read into the cache. wiredTiger.cache.pages read into cache with the wiredTiger.cache.pages written from cache can provide an overview of the I/O activity.

wiredTiger.cache.pages written from cache: Number of pages written from the cache. wiredTiger.cache.pages written from cache with the wiredTiger.cache.pages read into cache can provide an overview of the I/O activity.

To adjust the size of the WiredTiger internal cache, see --wiredTigerCacheSizeGB and storage.wiredTiger.engineConfig.cacheSizeGB. Avoid increasing the WiredTiger internal cache size above its default value. If your use case requires increased internal cache size, see --wiredTigerCacheSizePct and storage.wiredTiger.engineConfig.cacheSizePct.

wiredTiger.connection: A document that returns statistics related to WiredTiger connections.

wiredTiger.cursor: A document that returns statistics on WiredTiger cursor.

wiredTiger.data-handle: A document that returns statistics on the data handles and sweeps.

wiredTiger.log: A document that returns statistics on WiredTiger's write ahead log (i.e. the journal).
Tip
Journaling and the WiredTiger Storage Engine

wiredTiger.reconciliation: A document that returns statistics on the reconciliation process.

wiredTiger.session: A document that returns the open cursor count and open session count for the session.

wiredTiger.thread-yield: A document that returns statistics on yields during page acquisitions.

wiredTiger.transaction

A document that returns statistics on transaction checkpoints and operations.

wiredTiger.transaction.transaction checkpoint most recent time (msecs): Amount of time, in milliseconds, to create the most recent checkpoint. An increase in this value under stead write load may indicate saturation on the I/O subsystem.

Back

profile

shardConnPoolStats

Definition

Compatibility

Note

Syntax

Tip

Behavior

Initialization

Include mirroredReads

Output

Note

asserts

bucketCatalog

catalogStats

changeStreamPreImages

connections

Note

Note

defaultRWConcern

electionMetrics

Tip

Tip

extra_info

flowControl

globalLock

indexBuilds

indexBulkBuilder

indexStats

Instance Information

locks

logicalSessionRecordCache

Tip

Tip

mem

metrics

Note

Tip

Note

Note

mirroredReads

Tip

Tip

Tip

network

opLatencies

opWorkingTime

opReadConcernCounters

Warning

Removed

opWriteConcernCounters

Note

Note

Note

Note

opcounters

Note

opcountersRepl

oplogTruncation

planCache

profiler

queryStats

queryAnalyzers

queues

Important

Queue Information

querySettings

readConcernCounters

readPreferenceCounters

repl

security

Note

sharding

shardingStatistics

Note

shardedIndexConsistency

Tip

Tip

spillWiredTiger

storageEngine

tcmalloc

Note

Include `mirroredReads`