Diagnostic Commands
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buildInfo

For the buildInfo command, the response contains the following fields:
Field | Description |
---|---|
ok | Returns 1 for success or 0 for failure. |
version | MongoDB client compatibility version. This is the earliest
version of the MongoDB client with which the Data Federation service
is compatible. |
versionArray | MongoDB client compatibility version in array format. |
dataLake.version | Version number of Data Federation. |
dataLake.gitVersion | Git version of the Data Federation service. |
dataLake.date | Build timestamp of the Data Federation service. |
dataLake.mongoSQLVersion | mongoSQL version of the Data Federation service. |
Example
{ "ok" : <return>, "version" : "<version-number>", "versionArray" : [ <number>, <number>, <number>, <number> ], "dataLake" : { "version" : "<version-number>", "gitVersion" : "<version-number>", "date" : "<timestamp>", "mongoSQLVersion" : "<version-number>" } }
collStats

For the collStats command, Atlas Data Federation omits the following fields in the response:
avgObjSize
capped
max
maxSize
wiredTiger
nindexes
totalIndexSize
indexSizes
Atlas Data Federation includes the following fields in the response. You can use these fields to verify what partitions are used to populate a collection, understand how recently the stats were computed, and determine if Atlas Data Federation truncated the output document.
Field | Description | |
---|---|---|
dataLake.partitionCount | Number of partitions. | |
dataLake.avgPartitionSize | Average size of all partitions. | |
dataLake.partitions.format | File format of the partition. | |
dataLake.partitions.attributes | Filtering attributes of the partition. | |
dataLake.partitions.count | Number of documents in the partition. | |
dataLake.partitions.size | Size, in bytes, of the partition. | |
dataLake.partitions.source | S3 URL or Atlas cluster name, which contains the
backing data of the partition. | |
dataLake.partitions.version | MongoDB version of the Atlas cluster. The
For example, | |
cacheMetadata | Information about how recently Atlas Data Federation computed the statistics. | |
cacheMetadata.computeTime | Time in ISODate format when the computation
for the stats started. | |
cacheMetadata.automaticRefreshInProgress | Flag that indicates whether a background job is running now to
refresh the cache. | |
truncated | Flag that indicates whether Atlas Data Federation enforced the maximum document size limit of 16MiB. The flag value can be one of the following:
|
Example
{ ... "partitionCount": <number of partitions>, "avgPartitionSize": <average size of all partitions>, "partitions": [ { "format": <file format>, "attributes": <filtering attributes>, "count": <number of documents in partition>, "source": <S3 url or Atlas cluster name>, "size": <size, in bytes, of the partition> }, ... ], "truncated": false, "cacheMetadata": { computeTime: ISODate("2021-07-25T15:10:33.513Z"), automaticRefreshInProgress: false }, ... }
Atlas Data Federation introduces an optional boolean parameter, sync
, to bypass
the cache and fetch the most recent storage statistics for a given
collection. The following values are valid for the sync
parameter:
true
- to bypass the cache and return the most recent storage statisticsfalse
- to return cached data
If the sync
parameter is omitted, defaults to false
.
Example
db.runCommand( {collStats: "<string>", sync: true|false} )
To learn more about the parameters supported by this command, see collStats.
connectionStatus

For connectionStatus command, Atlas Data Federation returns information about the current connection, specifically the state of authenticated users and their available roles.
Note
Only one user can authenticate on a connection to a federated database instance at any
given time. If a user authenticates and then runs the db.auth()
command, Data Federation replaces the previous user's permissions with the new
user's permissions.
The connectionStatus
command shows only the newly authenticated user in the
authenticatedUsers
output field.
dbStats

For dbStats command, Atlas Data Federation
introduces an optional boolean parameter, sync
, to bypass the cache
and fetch the most recent storage statistics for a given database. The
following values are valid for the sync
parameter:
true
- to bypass the cache and return the most recent storage statisticsfalse
- to use the cached data also
If the sync
parameter is omitted, defaults to false
.
Example
db.runCommand( {dbStats: 1, sync: true|false} )
To learn more about the parameters supported by this command, see dbStats.
Atlas Data Federation command omits the followig fields in the response:
object
avgObjSize
fsUsedSize
fsTotalSize
The commands adds the following fields in the response. You can use these fields to determine whether the command returned stale data.
Field | Description |
---|---|
cacheMetadata | Contains information on how recently the stats were computed. |
cacheMetadata.computeTime | Time in ISODate format when the computation
for the stats started. |
cacheMetadata.automaticRefreshInProgress | Flag that indicates whether a background job is running now to
refresh the cache. |
explain

The explain command returns
information that describes the Data Federation query plan. The explain
output
differs from MongoDB in that it provides information about the data
partitions used to satisfy the query.
The following commands can be explained in Data Federation:
aggregate()
count()
find()
Usage
Atlas Data Federation supports the following verbosity
modes:
queryPlanner
- provides information on the query plan. If the verbosity is not specified, Atlas Data Federation defaults to this mode.queryPlannerExtended
- provides detailed information on the query plan including information about the object-storage objects, such as the object-storage object names and sizes that will be queried.executionStats
- provides query execution statistics and performance.
Atlas Data Federation doesn't support the allPlansExecution
mode.
Example
The following example shows how to use the explain
command to
get information about the aggregate command, including detailed
information on the query plan.
db.runCommand({ "explain": { "aggregate": "user", "verbosity": "queryPlannerExtended", "pipeline": [ ], "cursor": {} }})
The following example shows how to append a method to the
explain
method, such as the find()
method, to get query execution statistics on the query.
db.users.explain("executionStats").find({"type": "admin"})
Output
When you run explain
, Atlas Data Federation returns the following additional
fields for other partitions:
Output Field Name | Description |
---|---|
stats | Document that describes the number and total size of partitions
that Atlas Data Federation might open for the query. |
stats.size | Total size of partitions that Atlas Data Federation might open for the query. |
stats.numberOfPartitions | Number of partitions that Atlas Data Federation might open for the query. |
truncated | Boolean that indicates whether the explain output
is truncated. The explain total output document size is
limited to 16 MiB. |
plan | Document that contains the query execution plan for the query.
The document contains nested execution plan nodes, each of which
is a document describing the plan node. The nested plan node
documents contain internal description of Atlas Data Federation's query
execution, and include various node kinds that are subject to
change. Contact MongoDB support if you need more help with
understanding the query plan. |
getLog

For getLog command, Atlas Data Federation returns a successful response, but doesn't includes log data.
getMore

For getMore command, Atlas Data Federation returns subsequent batches of documents currently pointed to by a cursor, when used in conjunction with commands that return a cursor, e.g. find and aggregate.
hostInfo

For hostInfo command, Atlas Data Federation returns only the following subset of fields from the standard MongoDB response:
{ "ok" : <return>, "system" : { "currentTime" : ISODate("<timestamp>"), "hostname" : "<hostname>", "cpuAddrSize" : <number>, "memSizeMB" : <number>, "numCores" : <number>, "cpuArch" : "<identifier>", }, "os" : { "type" : "<string>", "name" : "<string>", }, "extra" : { } }
ping

For ping command, Atlas Data Federation tests whether a server is responding to commands.
whatsmyuri

For whatsmyuri command, Atlas Data Federation returns the client IP address.