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Metrics Reference for mongot

The mongot process exposes Prometheus metrics that describe its runtime health and performance across core areas of operation. This reference page describes key metrics that are relevant to day-to-day monitoring and troubleshooting. For the complete metric set, scrape the mongot Prometheus metrics endpoint at http://<mongot-host>:9946/metrics.

メトリクスを表示

To view the raw metrics that mongot exposes, send an HTTP GET request to the following mongot Prometheus metrics endpoint:

http://<mongot-host>:9946/metrics

In this endpoint:

<mongot-host> is the hostname or IP address of the mongot process.
9946 is the default port for the metrics endpoint. To configure the metrics endpoint port, see the metrics.address setting in the mongot configuration file.
/metrics is the path for the metrics endpoint.

The /metrics endpoint returns metrics in plain Prometheus text format. To monitor mongot metrics over time, configure your Prometheus instance to scrape this endpoint.

重要

The /metrics endpoint requires no authentication by default. For production deployments, restrict access at the network layer.

Metric Naming Conventions

mongot metric names use a consistent naming pattern:

All metric names start with the mongot_ prefix.
Metric names generally follow the pattern mongot_<area>_<measurement>[_<unit>], where:
- <area> indicates the subsystem or component the metric belongs to, such as process, jvm, replication, or index.
- <measurement> indicates what is being measured, such as cpu_usage, heap_memory, or index_size.
- <unit> (optional) indicates the unit or counter semantics for the metric. This optional suffix indicates either the unit that the metric is measured in, such as seconds, bytes, or ms, or the type of counter the metric represents, such as total, events, or operations.
  
  注意
  Some metric name suffixes don't reflect the actual reported unit for the metric. For example, mongot_index_stats_query_latency_seconds has the suffix _seconds, but mongot reports the metric in milliseconds, as indicated by the timeUnit=milliseconds label in the metric output. To confirm the unit for each metric, check the Unit value in the metric reference tables below.

In addition to the metric name, mongot metrics can include labels (also called dimensions). Labels distinguish multiple time series that share the same base metric name. For example, a metric might use labels to identify a state, status, index type, quantile, or a specific index.

For some metrics, you must interpret the metric as the combination of the metric name and its labels, not by the metric name alone. For example, mongot_replication_mongodb_indexManagerState uses the state label to expose one series for each replication state, such as STEADY_STATE or FAILED. Exactly one of those labeled series has the value 1 at a time. Per-index metrics similarly use labels such as generationId_logString and indexId_logString to distinguish one index from another.

For distribution metrics, the suffix of the metric name indicates the Prometheus series type:

Histograms expose _bucket, _count, _sum, and _max.
Summaries expose _count, _sum, and _max. Some summaries also include quantile labels such as {quantile="0.5"}.

Common Metric Labels

The following table describes common labels that appear in mongot metrics.

Label Name	Metric Scope	Possible Values
`name`	All executor pools	`executorMetrics`
`Scope`	Cross-cutting	`jvm`, `replication`, `lucene`
`generationId_logString`, `indexId_logString`	Most `mongot_index_stats_*` series	Internal opaque Ids (the per-index identifier that the logs use)
`indexFeatureVersion`	Many index metrics	`3`, `5`, `6` (the on-disk index format)
`indexType`	Indexing and initial-sync metrics	`search`, `vector_search`, `vector_search_auto_embedding` (only when you configure Automated Embedding)
`numPartitions`	Index size and document metrics	`1` for self-managed
`timeUnit`	Latency summary metrics	`seconds`, `milliseconds`, `microseconds`
`quantile`	Summary metrics	`0.5`, `0.75`, `0.9`, `0.99`
`state`	`indexManagerState`	`STEADY_STATE`, `INITIAL_SYNC`, `INITIAL_SYNC_BACKOFF`, `INITIALIZING`, `FAILED`, `FAILED_EXCEEDED`, `SHUT_DOWN`, `STEADY_STATE_SHUT_DOWN`
`status`	`indexStatusCode`	`STEADY`, `INITIAL_SYNC`, `FAILED`, `RECOVERING_NON_TRANSIENT`, `RECOVERING_TRANSIENT`, `STALE`, `NOT_STARTED`, `DOES_NOT_EXIST`, `UNKNOWN`
`clientName`	`mongot_mongoClient_connectionPool_*`	`mongot steady state sync`, `mongot initial sync and session refresh`, `mongot metadata service`, `mongot periodic optime fetcher`, `mongot database metadata resolver`, `mongot server info resolver`, `mongot Lease Manager mongo client`, `mongot AutoEmbedding Materialized View Writer` (only when Automated Embedding is enabled)

Key Metric Groups

Process and JVM Metrics

Use process and JVM metrics to confirm that mongot is running normally and to identify heap or garbage collection pressure.

プロセス

メトリクス	タイプ	単位	説明
`mongot_process_uptime_seconds`	ゲージ	秒	The uptime of the Java Virtual Machine.
`mongot_process_start_time_seconds`	ゲージ	unix seconds	Start time of the process since unix epoch.
`mongot_process_cpu_time_ns_total`	カウンター	ナノ秒	The "cpu time" used by the Java Virtual Machine process. Use `rate()` for instantaneous CPU consumption.
`mongot_process_cpu_usage`	ゲージ	0-1	The "recent cpu usage" for the Java Virtual Machine process.

JVM Memory

メトリクス	タイプ	単位	説明
`mongot_jvm_memory_used_bytes`	ゲージ	バイト	The amount of used memory. Labels: `area=heap\|nonheap`, `id=<pool>` (for example, G1 Eden Space, G1 Old Gen, G1 Survivor Space, Metaspace).
`mongot_jvm_memory_committed_bytes`	ゲージ	バイト	The amount of memory committed for the Java virtual machine to use.
`mongot_jvm_memory_max_bytes`	ゲージ	バイト	The maximum memory that can be used. For heap, `id="G1 Old Gen"` carries `-Xmx`.
`mongot_jvm_buffer_count_buffers`	ゲージ	count	NIO buffer pool counts. Labels: `id=direct\|mapped`.
`mongot_jvm_buffer_memory_used_bytes`	ゲージ	バイト	Memory the JVM uses for NIO buffer pools.
`mongot_jvm_buffer_total_capacity_bytes`	ゲージ	バイト	NIO buffer pool capacity.

JVM Garbage Collection

メトリクス	タイプ	単位	説明
`mongot_jvm_gc_pause_seconds`	概要	秒	Time spent in GC pause. No quantile labels. Use `mongot_jvm_gc_pause_seconds_max` for the longest recent pause.
`mongot_jvm_gc_concurrent_phase_time_seconds`	概要	秒	Time spent in concurrent GC phase.
`mongot_jvm_gc_live_data_size_bytes`	ゲージ	バイト	Size of long-lived heap memory pool after reclamation. The "live heap" to watch for memory pressure.
`mongot_jvm_gc_max_data_size_bytes`	ゲージ	バイト	Max size of long-lived heap memory pool.
`mongot_jvm_gc_memory_allocated_bytes_total`	カウンター	バイト	Increase in young heap pool size between GCs.
`mongot_jvm_gc_memory_promoted_bytes_total`	カウンター	バイト	Promotions from young into old generation.

System Metrics

Use system metrics to monitor host-level CPU, disk, memory, paging, and network conditions that can affect mongot.

CPU

メトリクス	タイプ	単位	説明
`mongot_system_cpu_count`	ゲージ	count	Processors available to the JVM.
`mongot_system_cpu_usage`	ゲージ	0–1	Recent system CPU usage.
`mongot_system_load_average_1m`	ゲージ	単位なし	OS 1-minute load average.

Disk

メトリクス	タイプ	単位	説明
`mongot_system_disk_space_data_path_free_bytes`	ゲージ	バイト	Free disk space on the `mongot` `dataPath` volume. Alert on this metric.
`mongot_system_disk_space_data_path_total_bytes`	ゲージ	バイト	Total disk space on the `dataPath` volume. Use to compute free %.
`mongot_system_disk_space_free_bytes`, `mongot_system_disk_space_total_bytes`	ゲージ	バイト	Free and total disk space across the file system (different scope than `data_path`).
`mongot_system_disk_readBytes_bytes`	ゲージ	バイト	Bytes read from disk per device. Label: `name=<device>` (e.g., `/dev/vda`).
`mongot_system_disk_writeBytes_bytes`	ゲージ	バイト	Bytes written per device.
`mongot_system_disk_reads_events`	ゲージ	count	Read I/O count per device. Use `rate()` for read IOPS.
`mongot_system_disk_writes_events`	ゲージ	count	Write I/O count per device.
`mongot_system_disk_currentQueueLength_tasks`	ゲージ	count	Disk queue length (I/Os in progress) per device.
`mongot_system_disk_transferTime_ms`	ゲージ	ミリ秒	Time spent reading or writing per device.

メモリ

メトリクス	タイプ	単位	説明
`mongot_system_memory_phys_total_bytes`	ゲージ	バイト	Total physical memory on the host.
`mongot_system_memory_phys_available_bytes`	ゲージ	バイト	Physical memory available.
`mongot_system_memory_phys_inUse_bytes`	ゲージ	バイト	Physical memory in use.
`mongot_system_memory_virt_inUse_bytes`	ゲージ	バイト	Total physical and virtual memory in use.
`mongot_system_memory_virt_swap_inUse_bytes`, `mongot_system_memory_virt_swap_available_bytes`, `mongot_system_memory_virt_swap_total_bytes`	ゲージ	バイト	Swap state.
`mongot_system_memory_virt_swap_pagesIn_operations`, `mongot_system_memory_virt_swap_pagesOut_operations`	ゲージ	count	Swap in/out activity.
`mongot_system_memory_memoryMappings_objects`	ゲージ	count	Number of memory mappings (relevant for Lucene mmap counts).
`mongot_system_memory_pageSize_bytes`	ゲージ	バイト	System page size.

ページフォールト

メトリクス	タイプ	単位	説明
`mongot_system_process_majorPageFaults_operations`	ゲージ	count	Major page faults. Use this metric with the storage class advisory threshold.
`mongot_system_process_minorPageFaults_operations`	ゲージ	count	Minor page faults.

ネットワーク

メトリクス	タイプ	単位	説明
`mongot_system_netstat_bytesRecv_bytes`, `mongot_system_netstat_bytesSent_bytes`	ゲージ	バイト	Bytes received and sent per interface (`name=eth0`).
`mongot_system_netstat_packetsRecv_events`, `mongot_system_netstat_packetsSent_events`	ゲージ	count	Packets received and sent.
`mongot_system_netstat_inErrors_events`, `mongot_system_netstat_outErrors_events`, `mongot_system_netstat_inDrops_events`, `mongot_system_netstat_collisions_events`	ゲージ	count	Error, drop, and collision counters.
`mongot_system_netstat_speed`	ゲージ	bits/sec	Negotiated interface speed.

レプリケーションメトリクス

Use replication metrics to determine whether mongot is healthy, syncing normally, and staying caught up with mongod.

Overall State

メトリクス	タイプ	単位	説明
`mongot_replication_manager`	ゲージ	0/1	`1` when the replication manager is active.
`mongot_replication_mongodb_manager`	ゲージ	0/1	`1` when the MongoDB-backed replication manager is active. Label: `type=normal`.
`mongot_replicationIndexManager_transitionState_total`	カウンター	count	State transitions. Labels: `fromState`, `toState`. Use to detect resyncs (`INITIALIZING` to `STEADY_STATE` transitions).

Session Refresher

メトリクス	タイプ	単位	説明
`mongot_replication_sessionRefresher_sessions`	ゲージ	count	Active sessions.
`mongot_replication_sessionRefresher_refreshes_total`	カウンター	count	Total session refreshes.
`mongot_replication_sessionRefresher_failedSessionRefreshes_total`	カウンター	count	Failed refreshes.
`mongot_replication_sessionRefresher_sessionRefreshDurations_seconds`	概要	秒	Refresh duration distribution.

Optime Updater

メトリクス	タイプ	単位	説明
`mongot_replicationOptimeUpdaterError_total`	カウンター	count	Optime-update errors.
`mongot_replicationOptimeUpdater_executor_*`	さまざまな	該当なし	Executor metrics for the optime updater.

Per-index Metrics

mongot emits the following metrics per index and includes generationId_logString and indexId_logString labels to identify the specific index. Filter by those labels to inspect a specific index, or aggregate across labels to understand fleet-wide behavior.

Index Status and Size

メトリクス	タイプ	単位	説明
`mongot_index_stats_indexStatusCode`	ゲージ	0/1	Per-index status. One-hot encoded across the `status` label values: `STEADY`, `INITIAL_SYNC`, `FAILED`, `RECOVERING_NON_TRANSIENT`, `RECOVERING_TRANSIENT`, `STALE`, `NOT_STARTED`, `DOES_NOT_EXIST`, `UNKNOWN`.
`mongot_index_stats_indexFeatureVersion`	ゲージ	数値	On-disk index format version. For example, `3`.
`mongot_index_stats_indexSizeBytes`	ゲージ	バイト	Total on-disk size of the index.
`mongot_index_stats_largestIndexFileSizeBytes`	ゲージ	バイト	Largest single file in the index.
`mongot_index_stats_numFilesInIndex`	ゲージ	count	Number of Lucene segment files.
`mongot_index_stats_numLuceneDocs`	ゲージ	count	Lucene documents in the index.
`mongot_index_stats_numLuceneMaxDocs`	ゲージ	count	Maximum Lucene document ID (includes deleted-not-merged).
`mongot_index_stats_numLuceneFields`	ゲージ	count	Number of indexed Lucene fields.
`mongot_index_stats_segment_count`	ゲージ	count	Number of Lucene segments.
`mongot_index_stats_requiredMemoryBytes`	ゲージ	バイト	Estimated required memory for the index.

Indexing Metrics

メトリクス	タイプ	単位	説明
`mongot_index_stats_indexing_replicationLagMs`	ゲージ	ミリ秒	Replication lag per index, in milliseconds. The unit is in the metric name (`Ms`). Do not divide by 1000 in PromQL unless you want to convert to seconds.
`mongot_index_stats_indexing_replicationOpTime`	ゲージ	BSON Timestamp	Last applied replication optime (numeric encoding).
`mongot_index_stats_indexing_maxPossibleReplicationOpTime`	ゲージ	BSON Timestamp	Cap on advance, set by `mongod` tip.
`mongot_index_stats_indexing_insert_total`, `mongot_index_stats_indexing_update_total`, `mongot_index_stats_indexing_delete_total`	カウンター	count	Indexing operation counts. Label: `indexType=search`.
`mongot_index_stats_indexing_totalBytesProcessed_total`	カウンター	バイト	Total bytes processed by indexing.
`mongot_index_stats_indexing_vectorFieldsIndexed_total`	カウンター	count	Vector fields indexed.
`mongot_index_stats_indexing_commitDurations_seconds`	概要	seconds (`timeUnit=milliseconds`)	Per-index commit durations.
`mongot_index_stats_indexing_indexingBatchDurations_seconds`	概要	秒	Batch duration distribution.
`mongot_index_stats_indexing_largeChangeStreamEvents_total`	カウンター	count	Oversized change-stream events. Label: `threshold=10MiB\|12MiB\|14MiB\|15MiB`.
`mongot_index_stats_indexing_invalidGeometryField_total`	カウンター	count	Documents rejected for invalid geometry.
`mongot_index_stats_indexing_sortableStringTruncated_total`	カウンター	count	Truncated sortable strings.
`mongot_index_stats_indexing_initialSyncExceptions_total`	カウンター	count	Exceptions during initial sync.
`mongot_index_stats_indexing_steadyStateExceptions_total`	カウンター	count	Steady-state exceptions.
`mongot_index_stats_indexing_consecutiveInitialSyncResyncExceptions`	ゲージ	count	Consecutive initial-sync resync exceptions for this index.

クエリメトリクス

メトリクス	タイプ	単位	説明
`mongot_index_stats_query_totalQueries_total`	カウンター	count	Total queries issued against the index.
`mongot_index_stats_query_totalHitsCount_total`	カウンター	count	Total hits returned.
`mongot_index_stats_query_failedQueries_total`	カウンター	count	Queries that failed.
`mongot_index_stats_query_internallyFailedQueries_total`, `mongot_index_stats_query_invalidQueries_total`, `mongot_index_stats_query_npeQueries_total`, `mongot_index_stats_query_lenientFailures_total`	カウンター	count	Specific failure-class counters.
`mongot_index_stats_query_searchResultBatchLatencies_seconds`	概要	seconds (`timeUnit=milliseconds`)	Search batch latency. This is the headline query-latency metric.
`mongot_index_stats_query_luceneTopDocsSearchLatencies_seconds`	概要	seconds (`timeUnit=milliseconds`)	Latency inside Lucene's TopDocs search. Use this metric to distinguish Lucene-internal latency from total latency.
`mongot_index_stats_query_vectorResultLatencies_seconds`	概要	seconds (`timeUnit=milliseconds`)	Vector search result latency.
`mongot_index_stats_query_vectorSearchInitialTopDocsLatencyTimer_seconds`, `mongot_index_stats_query_vectorSearchGetMoreTopDocsLatencyTimer_seconds`	概要	seconds (`timeUnit=milliseconds`)	Vector search latency phases.
`mongot_index_stats_query_tokenFacetsStateRefreshLatency_seconds`	概要	seconds (`timeUnit=milliseconds`)	Facets state-refresh latency.
`mongot_index_stats_query_batchDataSize`, `mongot_index_stats_query_batchDocumentCount`	概要	bytes / count	Per-batch payload size and document count.
`mongot_index_stats_query_limitPerQuery`	histogram	count (`le=10\|50\|100\|200\|500\|1000\|+Inf`)	Distribution of `$search` and `$vectorSearch` limits.
`mongot_index_stats_query_numCandidatesPerQuery`	histogram	count	Vector candidates per query, bucketed by quantization.
`mongot_index_stats_query_getMoreCommandCalls_total`, `mongot_index_stats_query_getMoreCommandCallsPerQuery`	counter / summary	count	`getMore` call counts.
`mongot_index_stats_query_batchWithTies_total`	カウンター	count	Result batches with score ties.
`mongot_index_stats_query_benefitFromIndexSortCount_total`	カウンター	count	Queries that benefited from index sort optimization.
`mongot_index_stats_query_extractableLimitQueries_total`, `mongot_index_stats_query_extractableLimitSecondBatchQueries_total`	カウンター	count	Limit-extraction optimizations triggered.
`mongot_index_stats_query_phantomSearcherCleanupCount_total`	カウンター	count	Phantom-searcher cleanups.
`mongot_index_stats_query_orphanedDeletedDocsRatio`	概要	ratio	Deleted-document ratio in returned results.
`mongot_index_stats_query_noProgressBatches_total`	カウンター	count	Batches that made no forward progress.
`mongot_index_stats_query_vectorCommandCalls_total`, `mongot_index_stats_query_vectorRescoringFailureCount_total`, `mongot_index_stats_query_vectorSearchQueriesOverSearchIndexes_total`	カウンター	count	Vector-specific counters.
`mongot_index_stats_query_feature_total`	カウンター	count	Per-query-feature usage. Label: `name=<feature>`. For example, `compound`, `text`, `phrase`, `near`, `vectorSearch`, `knnBeta`, `autoEmbedding` (only when Automated Embedding is enabled).
`mongot_index_stats_query_failedExplainQueryAggregate_total`	カウンター	count	Failed `$explain` aggregates.

Per-index Replication Breakdown

メトリクス	タイプ	単位	説明
`mongot_replication_mongodb_indexManagerState`	ゲージ	0/1	The canonical replication-state signal. `mongot` one-hot encodes this metric, meaning that exactly one `state` label is `1.0`. States: `STEADY_STATE`, `INITIAL_SYNC`, `INITIAL_SYNC_BACKOFF`, `INITIALIZING`, `FAILED`, `FAILED_EXCEEDED`, `SHUT_DOWN`, `STEADY_STATE_SHUT_DOWN`.
`mongot_index_stats_replication_steadyState_batchTotalApplicableBytes`, `mongot_index_stats_replication_steadyState_batchTotalApplicableDocuments`	概要	bytes / count	Steady-state batch sizes.
`mongot_index_stats_replication_steadyState_decodingBatchDurations_seconds`	概要	秒	Steady-state decoding duration.
`mongot_index_stats_replication_steadyState_getMoreDurations_seconds`	概要	秒	Steady-state `getMore` duration.
`mongot_index_stats_replication_initialSync_changeStream_*`	概要	—	Initial-sync change-stream phase metrics (mirrors steady state).
`mongot_index_stats_replication_initialSync_collScan_*`	概要	—	Initial-sync collection-scan phase metrics.

Lucene Refresh Latency

メトリクス	タイプ	単位	説明
`mongot_index_stats_luceneIndexRefresher_refreshDurations_seconds`	概要	seconds (`timeUnit=milliseconds`)	Lucene IndexReader refresh latency.

Command Metrics

mongot accepts the following set of named commands from mongod:

buildinfo
getMore
hello
isMaster
ismaster
killCursors
manageSearchIndex
ping
planShardedSearch
search
vectorSearch

For each command, mongot exposes the following metrics, where <name> is a placeholder for the command name:

パターン	タイプ	説明
`mongot_command_<name>CommandFailure_total`	カウンター	Failure count for the command.
`mongot_command_<name>CommandTotalLatency_seconds`	概要	End-to-end latency including serialization.
`mongot_command_<name>CommandSerializationLatency_seconds`	概要	Serialization latency (subset; not all commands).

Tip

Monitor Search and Vector Search Latency Across Indexes

mongot_command_searchCommandTotalLatency_seconds and mongot_command_vectorSearchCommandTotalLatency_seconds are the primary metrics to monitor for $search and $vectorSearch latency aggregates. These expose latency aggregates for all search and vectorSearch commands across all indexes.

Indexing Scheduler and Dispatcher Metrics

Use indexing scheduler and dispatcher metrics to identify backlog, saturation, and slow work in replication and indexing pipelines.

Steady-state Change-stream Pipeline

メトリクス	タイプ	単位	説明
`mongot_indexing_steadyStateChangeStream_batchesInProgressTotal`	ゲージ	count	Batches currently being applied. Label: `indexType=search\|vector_search\| vector_search_auto_embedding` (only when you enable Automated Embedding).
`mongot_indexing_steadyStateChangeStream_batchesInProgressTotalDurations_seconds`	概要	秒	Duration distribution for in-flight batches.
`mongot_indexing_steadyStateChangeStream_getMoreDurations_seconds`	概要	秒	`getMore` round-trip distribution.
`mongot_indexing_steadyStateChangeStream_getMoresInFlight`	ゲージ	count	`getMore` requests in flight.
`mongot_indexing_steadyStateChangeStream_getMoresScheduled`	ゲージ	count	Scheduled `getMore` requests by `indexType`.
`mongot_indexing_steadyStateChangeStream_getMoresSchedulingDurations_seconds`	概要	秒	`getMore` scheduling latency.
`mongot_indexing_steadyStateChangeStream_preprocessingBatchDurations_seconds`	概要	秒	Pre-processing duration per batch.
`mongot_indexing_steadyStateChangeStream_witnessedChangeStreamUpdates_total`	カウンター	count	Total change-stream events observed. Label: `Scope=replication`.
`mongot_indexing_steadyStateChangeStream_applicableChangeStreamUpdates_total`	カウンター	count	Events that `mongot` considered applicable.
`mongot_indexing_steadyStateChangeStream_dispatcher`	ゲージ	0/1	Dispatcher status. Labels: `Scope=replication`, `client=synchronous-batch`.
`mongot_indexing_steadyStateChangeStream_skippedChangeStreamDocumentsWithoutMetadataNamespace_total`	カウンター	count	Events skipped due to missing metadata.
`mongot_indexing_steadyStateChangeStream_unexpectedBatchFailures_total`	カウンター	count	Unexpected batch failures.
`mongot_indexing_steadyStateChangeStream_rescheduledEmbeddingGetMores_total`	カウンター	count	Rescheduled embedding getMores. This metric is only available when you configure Automated Embedding.
`mongot_indexing_changeStreamModeSelector_failedSamplingAttemptsCounter_total`	カウンター	count	Failed change-stream mode sampling attempts.

Indexing Work Scheduler

Indexing work scheduler metrics monitor the queueing and execution of indexing batches.

メトリクス	タイプ	単位	説明
`mongot_indexingWorkScheduler_queuedBatchesTotal`, `mongot_indexingWorkScheduler_queuedEventsTotal`	ゲージ	count	Scheduler queue depth.
`mongot_indexingWorkScheduler_enqueueCalls_total`, `mongot_indexingWorkScheduler_dequeueCalls_total`	カウンター	count	Enqueue and dequeue counts.
`mongot_indexingWorkScheduler_indexingBatchDistribution`	概要	count	Distribution of batch sizes. Label: `Scope=replication`.
`mongot_indexingWorkScheduler_indexingBatchDurations_seconds`	概要	秒	Batch durations.
`mongot_indexingWorkScheduler_indexingBatchSchedulingDurations_seconds`	概要	秒	Scheduling overhead.

Decoding Work Scheduler

Decoding work scheduler metrics monitor the queueing and execution of change-stream batch decoding.

メトリクス	タイプ	単位	説明
`mongot_decodingWorkScheduler_queuedBatchesTotal`, `mongot_decodingWorkScheduler_queuedEventsTotal`	ゲージ	count	Scheduler queue depth.
`mongot_decodingWorkScheduler_enqueueCalls_total`, `mongot_decodingWorkScheduler_dequeueCalls_total`	カウンター	count	Enqueue and dequeue counts.
`mongot_decodingWorkScheduler_decodingBatchDistribution`	概要	count	Distribution of batch sizes. Label: `Scope=replication`.
`mongot_decodingWorkScheduler_decodingBatchDurations_seconds`	概要	秒	Batch durations.
`mongot_decodingWorkScheduler_decodingBatchSchedulingDurations_seconds`	概要	秒	Scheduling overhead.

Initial Sync, Lifecycle, and Config Metrics

Use these metrics to track index startup work, recovery, and catalog state.

最初の同期

注意

Some mongot metrics are phase-specific and populate only when the corresponding code path is active. For example, steady-state replication metrics, such as mongot_index_stats_indexing_replicationLagMs and the mongot_index_stats_replication_steadyState_* series, do not populate while an index is in initial sync. Conversely, initial-sync-specific metrics, such as mongot_initialsync_* and mongot_index_stats_replication_initialSync_*, are only relevant while initial sync is running or has run.

メトリクス	タイプ	単位	説明
`mongot_initialsync_queue_queuedSyncs`	ゲージ	count	Queued initial syncs. Label: `indexType`.
`mongot_initialsync_queue_requeuedEmbeddingInitialSyncs_total`	カウンター	count	Embedding initial syncs that were requeued. This metric is only available when you configure Automated Embedding.
`mongot_initialsync_dispatcher_inProgressSyncs`	ゲージ	count	Initial syncs currently in progress. Label: `indexType`.
`mongot_initialsync_dispatcher_queuedSyncs`	ゲージ	count	Initial syncs queued at the dispatcher.
`mongot_initialsync_dispatcher_inProgressResumedSyncs`	ゲージ	count	In-progress syncs that resumed from a checkpoint.
`mongot_initialsync_dispatcher_collectionScan`	ゲージ	0/1	Active collection-scan mode. Label: `scan_type=id_order\|natural_order`.
`mongot_initialsync_dispatcher_completedSyncDuration_seconds`	概要	秒	Completed sync duration distribution.
`mongot_initialsync_dispatcher_syncDuration_seconds`	概要	秒	Ongoing sync duration.
`mongot_initialsync_dispatcher_inProgressInitialSyncDurationMin_seconds`, `mongot_initialsync_dispatcher_inProgressInitialSyncDurationMax_seconds`, `mongot_initialsync_dispatcher_inProgressInitialSyncDurationSum_seconds`	ゲージ	秒	Min, max, and sum of in-progress initial sync durations.
`mongot_initialsync_dispatcher_unreadableDroppedIndexes_total`	カウンター	count	Dropped because their on-disk segments could not be read.
`mongot_initialsync_dispatcher_unreadableIndexRecoveries_total`	カウンター	count	Recovered after unreadable segments. Label: `unreadableIndexCause=corruptIndex\|incompatibleCodec\| incompatibleIndexFormat`.

ライフサイクル

メトリクス	タイプ	単位	説明
`mongot_lifecycle_indexesInInitializedState`	ゲージ	count	Indexes currently in the initialized state.
`mongot_lifecycle_indexInitializationDuration_seconds`	概要	秒	Initialization durations.
`mongot_lifecycle_failedDownloadIndexes_total`	カウンター	count	Index downloads that failed.
`mongot_lifecycle_failedDropIndexes_total`	カウンター	count	Index drops that failed.
`mongot_lifecycle_failedInitializationIndexes_total`	カウンター	count	Index initializations that failed.

Config State

メトリクス	タイプ	単位	説明
`mongot_configState_indexesInCatalog`	ゲージ	count	Indexes currently in the catalog. Labels: `Scope=replication`, `indexFormatVersion`.
`mongot_configState_indexesPhasingOut`	ゲージ	count	Indexes being phased out.
`mongot_configState_stagedIndexes`	ゲージ	count	Staged but not yet active indexes.
`mongot_configState_indexesInCatalogFeatureVersionFour`, `mongot_configState_indexesPhasingOutFeatureVersionFour`, `mongot_configState_stagedIndexesFeatureVersionFour`	ゲージ	count	Feature-version-4-specific equivalents.

Cursors and Index Factory

Use these metrics to monitor open cursor state and to detect indexes that mongot dropped or recovered because their on-disk segments were unreadable.

メトリクス	タイプ	単位	説明
`mongot_cursorManager_trackedCursors`	ゲージ	count	Currently tracked open cursors.
`mongot_indexFactory_unreadableDroppedIndexes_total`	カウンター	count	Indexes dropped because their segments were unreadable.
`mongot_indexFactory_unreadableIndexRecoveries_total`	カウンター	count	Recoveries after unreadable segments. Label: `unreadableIndexCause`.

Lucene Merge

Use these metrics to monitor Lucene segment merge activity, including the number and size of merges in progress, merge input and output sizes, merge durations, and merges discarded by the disk-utilization merge policy.

メトリクス	タイプ	単位	説明
`mongot_mergeScheduler_currentlyRunningMerges`	ゲージ	count	Active merges. Label: `Scope=lucene`.
`mongot_mergeScheduler_currentlyMergingDocs`	ゲージ	count	Documents currently being merged.
`mongot_mergeScheduler_numMerges_total`	カウンター	count	Total merges executed since startup.
`mongot_mergeScheduler_numSegmentsMerged_total`	カウンター	count	Segments folded by merges.
`mongot_mergeScheduler_mergeSize`	概要	バイト	Distribution of merge input sizes.
`mongot_mergeScheduler_mergeResultSize`	概要	バイト	Distribution of merge output sizes.
`mongot_mergeScheduler_mergedDocs`	概要	count	Documents-per-merge distribution.
`mongot_mergeScheduler_mergeTime_seconds`	概要	秒	Merge duration distribution.
`mongot_diskUtilizationAwarenessMergePolicy_discardedMerge_total`	カウンター	count	Merges discarded by the disk-utilization-aware policy.

MongoDB Client Connection Pool Metrics

mongot opens multiple named connection pools to mongod, and labels each pool with a clientName label that identifies the role of each pool. The following table lists possible clientName label values and their corresponding role:

clientName	目的
`mongot steady state sync`	Steady-state change-stream replication.
`mongot initial sync and session refresh`	Initial sync and session refresh. The `appName` seen in `mongod` `currentOp`.
`mongot metadata service`	Internal metadata service.
`mongot periodic optime fetcher`	Optime polling.
`mongot database metadata resolver`	Database metadata lookups.
`mongot server info resolver`	Server-info lookups.
`mongot Lease Manager mongo client`	Lease manager.
`mongot AutoEmbedding Materialized View Writer`	Automated embedding writes. This connection pool only appears when you configure Automated Embedding.

The following table lists the available metrics for mongot connection pools:

メトリクス	タイプ	単位	説明
`mongot_mongoClient_connectionPool_connections`	ゲージ	count	Currently open connections in the pool.
`mongot_mongoClient_connectionPool_connectionsCheckedOut`	ゲージ	count	Connections currently checked out.
`mongot_mongoClient_connectionPool_maxSize`	ゲージ	count	Configured max pool size.
`mongot_mongoClient_connectionPool_minSize`	ゲージ	count	Configured min pool size.
`mongot_mongoClientBuilder_successfulOpenSSLDynamicLinking_total`	カウンター	count	Successful native OpenSSL link attempts.
`mongot_mongoClientBuilder_failedOpenSSLDynamicLinking_total`	カウンター	count	Failed native OpenSSL link attempts.

シノニム

Use these metrics to monitor synonym synchronization activity, including collection scans, scan and sync durations, queue depth, and exceptions encountered during synonym sync.

メトリクス	タイプ	単位	説明
`mongot_synonymSync_collScans_total`	カウンター	count	Total collection scans performed for synonyms.
`mongot_synonymSync_collScansTriggeredByChangeStream_total`	カウンター	count	Synonym scans triggered by change-stream events.
`mongot_synonymSync_collScanDurations_seconds`	概要	秒	Scan duration distribution.
`mongot_synonymSync_syncDurations_seconds`	概要	秒	Sync duration distribution.
`mongot_synonymSync_queueDepth`	ゲージ	count	Current synonym sync queue depth.
`mongot_synonymSync_exceptions_total`	カウンター	count	Synonym sync exceptions.

Executor Pools

Use these metrics to monitor the named executor pools that mongot uses to run background work. Each pool exposes the same set of sub-metrics, prefixed with the pool name, so you can track thread activity, pool sizing, queue depth, task throughput, and per-task execution time across all pools.

The following table lists the sub-metrics that every executor pool exposes, where <pool> is the pool name prefix. All executor-pool sub-metrics carry the label name="executorMetrics".

Sub-Metric Suffix	タイプ	説明
`<pool>_active_threads`	ゲージ	Threads currently executing tasks.
`<pool>_pool_core_threads`, `<pool>_pool_max_threads`, `<pool>_pool_size_threads`	ゲージ	Pool sizing.
`<pool>_queued_tasks`	ゲージ	Tasks waiting for a thread — the saturation signal.
`<pool>_queue_remaining_tasks`	ゲージ	Remaining queue capacity.
`<pool>_completed_tasks_total`	カウンター	Tasks completed since startup.
`<pool>_idle_seconds`	概要	Time threads spent idle between tasks.
`<pool>_seconds`	概要	Per-task execution time.
`<pool>_scheduled_once_total`, `<pool>_scheduled_repetitively_total`	カウンター	Scheduled task counts (for scheduling pools).

The following table lists the prefixes for all available named executor pools and their respective purposes:

Executor Pool Prefix	What it runs
`mongot_blobstore_lifecycle_executor`	Blob-store lifecycle work.
`mongot_blocking_server_worker_executor`	Blocking gRPC server worker threads.
`mongot_change_stream_mode_selector_executor`	Change-stream mode selection.
`mongot_change_stream_sync_dispatcher_executor`	Change-stream sync dispatching (one of the busiest in steady state).
`mongot_config_monitor_executor`	Config-monitor polling.
`mongot_decoding_executor`	Decoding pipeline workers.
`mongot_disk_monitor_executor`	Disk-monitor polling.
`mongot_grpc_health_check_executor`	gRPC health check timer.
`mongot_idle_cursor_killer_executor`	Idle cursor reaping.
`mongot_index_commit_executor`	Index commit operations.
`mongot_index_lifecycle_executor`	Per-index lifecycle work.
`mongot_index_refresh_executor`	Lucene IndexReader refreshes.
`mongot_indexing_work_executor`	Indexing pipeline workers (the busiest indexing pool in steady state).
`mongot_indexing_lifecycle_executor`	Indexing-lifecycle work.
`mongot_indexing_auto_embedding_executor`	Automated-embedding indexing path. This executor pool only appears when you configure Automated Embedding.
`mongot_init_lifecycle_executor`	Init-time lifecycle work.
`mongot_mat_view_commit_executor`, `mongot_mat_view_leader_heartbeat_executor`, `mongot_mat_view_optime_updater_executor`, `mongot_mat_view_status_refresh_executor`, `mongot_materialized_view_lifecycle_executor`	Materialized-view tracking and lifecycle. These metrics are only available when Automated Embedding or other materialized-view-backed features are configured.
`mongot_replicationOptimeUpdater_executor`	Optime updater (background).
`mongot_session_refresh_executor`	Session refresher.
`mongot_system_metrics_updater_executor`	System metrics updater.

Tip

Watch Saturation Across All Executor Pools

To monitor saturation across all executor pools, run the following PromQL query:

max by (pool) (
  label_replace(
    {__name__=~"mongot_.+_executor_queued_tasks"},
    "pool", "$1", "__name__", "mongot_(.+)_executor_queued_tasks"
  )
)

This query returns the queued-task count for each executor pool.

Prometheus Server Self-Metrics

The following metric is available for the embedded Prometheus server in mongot:

メトリクス	タイプ	単位	説明
`mongot_prometheus_server_scraping_timer_seconds`	概要	seconds (`timeUnit=milliseconds`)	How long `mongot` takes to assemble a `/metrics` response. Sustained growth here means metric exposition itself is slowing down.

Configuration-Specific Metrics

The following metric families appear in the /metrics output only when you enable specific features.

Metric Family	説明	Availability in Self-Managed `mongot`
`mongot_embedding`	Metrics related to Automated Embedding. For example, `mongot_initialsync_queue_requeuedEmbeddingInitialSyncs_total`, `mongot_materialized_view_lifecycle_executor`, and connection-pool entries with `clientName="mongot AutoEmbedding Materialized View Writer"`.	Appear only when you configure Automated Embedding.
`mongot_mongot_ftdc_executor_failure_total`	Failure count for the FTDC executor.	Appears only when you enable the `ftdcExecutorMetricsToPrometheus` feature flag.

PromQL Examples

Most latency metrics in this catalog are summaries, not histograms, so use their published quantile labels directly when they exist. A smaller number of metrics, such as mongot_index_stats_query_limitPerQuery and mongot_index_stats_query_numCandidatesPerQuery, are histograms and expose _bucket series.

# Replication state
max by (state) (mongot_replication_mongodb_indexManagerState == 1)
# Maximum replication lag across all indexes, converted to seconds
max(mongot_index_stats_indexing_replicationLagMs) / 1000
# Index count by status
count by (status) (mongot_index_stats_indexStatusCode == 1)
# Search query p99 latency across all indexes
max(mongot_index_stats_query_searchResultBatchLatencies_seconds{quantile="0.99"})
# Worst recent GC pause
max(mongot_jvm_gc_pause_seconds_max)
# Average GC pause over 5 minutes
rate(mongot_jvm_gc_pause_seconds_sum[5m]) / rate(mongot_jvm_gc_pause_seconds_count[5m])
# Free disk percentage on dataPath
mongot_system_disk_space_data_path_free_bytes
  / mongot_system_disk_space_data_path_total_bytes
# Major page fault rate
rate(mongot_system_process_majorPageFaults_operations[5m])
# Steady-state and initial sync exceptions over 15 minutes
sum(rate(mongot_index_stats_indexing_steadyStateExceptions_total[15m]))
sum(rate(mongot_index_stats_indexing_initialSyncExceptions_total[15m]))

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