MongoDB 5

This page describes the Optimization Pack for MongoDb version 5.x.

Metrics

Documents & Operations

Name	Unit	Description
mongodb_opcounters_insert	operations/s	The number of insert operations received per second.
mongodb_opcounters_query	operations/s	The number of queries received per second.
mongodb_opcounters_update	operations/s	The number of update operations received per second
mongodb_opcounters_delete	operations/s	The number of delete operations received per second.
mongodb_opcounters_getmore	operations/s	The number of getMore operations received per second. This counter can be high even if the query count is low. Secondary nodes send getMore operations as part of the replication process.
mongodb_opcounters_command	operations/s	The number of command operations received per second. It counts all commands except the write commands (insert, update, and delete).
mongodb_documents_deleted	documents/s	The number of documents deleted per second.
mongodb_documents_inserted	documents/s	The number of documents inserted per second.
mongodb_documents_returned	documents/s	The number of documents returned per second.
mongodb_documents_updated	documents/s	The number of documents updated per second.

Transactions

Name	Unit	Description
mongodb_wt_concurrentTransactions_read_out	tickets	Number of read tickets in use
mongodb_wt_concurrentTransactions_write_out	tickets	Number of write tickets in use
mongodb_wt_concurrentTransactions_read_available	tickets	Number of read tickets remaining. When it reaches 0, read requests will be queued. The maximum number of read operations is controlled with wiredTigerConcurrentReadTransactions (or by adding more shards)
mongodb_wt_concurrentTransactions_write_available	tickets	Number of write tickets remaining. When it reaches 0, write requests will be queued. The maximum number of read operations is controlled with wiredTigerConcurrentWriteTransactions (or by adding more shards)
mongodb_wt_transaction_most_recent_time	milliseconds	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.
mongodb_metrics_cursor_open_total	cursors	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, stale tailable cursors, or a large number of operations this value may rise.
mongodb_metrics_cursor_timedOut	cursors	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.

Connections

Name	Unit	Description
mongodb_connections_current	connections	The number of incoming connections from clients to the database server, including connections from other servers such as replica set members or instances
mongodb_connections_available	connections	The number of unused incoming connections available.
mongodb_connections_active	connections	The number of active client connections to the server. This refers to client connections that currently have operations in progress.

Other metrics

Name	Unit	Description
mongodb_mem_resident	megabytes	The number of incoming connections from clients to the database server, including connections from other servers such as replica set members or instances
mongodb_mem_virtual	megabytes	The number of unused incoming connections available.
mongodb_extra_info_page_faults	faults/s	The number of active client connections to the server. This refers to client connections that currently have operations in progress.
mongodb_wt_cache_bytes_currently_in_the_cache	bytes	Size in byte of the data currently in WiredTiger internal cache.
mongodb_wt_cache_maximum_bytes_configured	bytes	Maximum WiredTiger internal cache size.
mongodb_wt_cache_unmodified_pages_evicted	pages/s	Number of unmodified pages evicted from the cache per second
mongodb_wt_cache_modified_pages_evicted	pages/s	Number of modified pages evicted from the cache per second
mongodb_wt_cache_tracked_dirty_bytes_in_the_cache	bytes/s	Size in bytes of the dirty data in the cache.
mongodb_wt_cache_pages_read_into_cache	pages/s	The number of pages read into the cache per second. Together with the write metric, it can provide an overview of the I/O activity.
mongodb_wt_cache_pages_written_from_cache	pages/s	The number of pages written from the cache. Together with the read metric, it can provide an overview of the I/O activity.
mongodb_wt_cache_pages_read_into_cache	pages/s	Number of pages read into the cache per second. Together with the write metric, it can provide an overview of the I/O activity.
mongodb_wt_cache_pages_written_from_cache	pages	Number of pages written from the cache. Together with the read metric, it can provide an overview of the I/O activity.
mongodb_globalLock_currentQueue_total	operations	The total number of operations queued waiting for the lock (sum of readers and writers). A consistently small queue, particularly of shorter operations, should cause no concern.
mongodb_globalLock_currentQueue_readers	operations	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.
mongodb_globalLock_currentQueue_writers	operations	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.
mongodb_globalLock_activeClients_total	operations	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 readers and writers to the inclusion of system threads.
mongodb_globalLock_activeClients_readers	operations	The number of the active client connections performing read operations.
mongodb_globalLock_activeClients_writers	operations	The number of the active client connections performing write operations.

Parameters

Name	Unit	Type	Default	Domain	Restart	Description
mongodb_cursorTimeoutMillis	milliseconds	integer	600000	0 → 1200000	no	Sets the expiration threshold in milliseconds for idle cursors before MongoDB removes them
mongodb_notablescan		categorical	false	true, false	no	Return an error when executing queries that don't use indices.
mongodb_ttlMonitorEnabled		categorical	true	true, false	no	Disable the TTL monitor works, preventing TTL documents removal
mongodb_disableJavaScriptJIT		categorical	true	true, false	no	The MongoDB JavaScript engine uses SpiderMonkey, which implements Just-in-Time (JIT) compilation for improved performance when running scripts
mongodb_maxIndexBuildMemoryUsageMegabytes	megabytes	Integer	200	50 → 2000	no	Limits the amount of memory that simultaneous index builds on one collection may consume for the duration of the builds. The memory consumed by an index build is separate from the WiredTiger cache memory.
mongodb_tcmallocReleaseRate		real	1.0	0.0 → 10.0	no	Rate at which we release unused memory to the system, via madvise(MADV_DONTNEED), on systems that support it. Zero means we never release memory back to the system.
mongodb_journalCommitInterval	milliseconds	integer	100	1 → 500	no	The number of milliseconds (ms) between journal commits.
mongodb_syncdelay		integer	60	0 → 300	no	The interval in seconds between fsync operations where mongod flushes its working memory to disk. By default, mongod flushes memory to disk every 60 seconds. In almost every situation you should not set this value and use the default setting.
mongodb_internalQueryEnableSlotBasedExecutionEngine		categorical	true	true, false	no	Use enhanced query execution when possible.
mongodb_planCacheSize	percent	integer	5	0 → 99	no	The size of the plan cache for the enhanced query execution engine.
mongodb_wterc_cache_overhead		integer	8	0 → 30	no	Amount of additional heap to allocate expressed as a percentage of the heap.
mongodb_wterc_cache_size	megabytes	integer	100	0 → 10000000	no	Maximum heap memory to allocate for the cache. A database should configure either cache_size or shared_cache but not both. This should correspond to the value used in MongoDB, so set it to a minimum of 256 MB or to 50% of (RAM - 1 GB)
mongodb_wterc_checkpoint_log_size	bytes	integer	0	0 → 2000000000	no	Minimum number of bites to be written between checkpoints. Setting the value to 0 configures periodic checkpoints.
mongodb_wterc_checkpoint_wait	seconds	integer	0	0 → 10000000	no	Seconds to wait between periodic checkpoints.
mongodb_wterc_eviction_threads_max		integer	8	1 → 20	no	Maximum number of threads WiredTiger will start to help evict pages from cache.
mongodb_wterc_eviction_threads_min		integer	1	1 → 20	no	Minimum number of threads WiredTiger will start to help evict pages from cache.
mongodb_wterc_eviction_checkpoint_target	percent	integer	1	0 → 99	no	Perform eviction at the beginning of checkpoints to bring the dirty content in cache to this level, expressed as a percentage of the total cache size. Ignored if set to zero or in_memory is true.
mongodb_wterc_eviction_dirty_target	percent	integer	5	0 → 99	no	Perform eviction in worker threads when the cache contains at least this much dirty content, expressed as a percentage of the total cache size.
mongodb_wterc_eviction_dirty_trigger	percent	integer	20	0 → 99	no	Trigger application threads to perform eviction when the cache contains at least this much dirty content, expressed as a percentage of the total cache size. This setting only alters behavior if it is lower than eviction_trigger.
mongodb_wterc_eviction_target	percent	integer	80	0 → 99	no	Perform eviction in worker threads when the cache contains at least this much content, expressed as a percentage of the total cache size. Must be less than eviction_trigger.
mongodb_wterc_eviction_trigger	percent	integer	95	0 → 99	no	Trigger application threads to perform eviction when the cache contains at least this much content, expressed as a percentage of the total cache size.
mongodb_wterc_file_manager_close_handle_minimum		integer	250	0 → 1000	no	Number of handles open before the file manager will look for handles to close.
mongodb_wterc_file_manager_close_idle_time	seconds	integer	30	0 → 100000	no	Amount of time in seconds a file handle needs to be idle before attempting to close it. A setting of 0 means that idle handles are not closed.
mongodb_wterc_file_manager_close_scan_interval	seconds	integer	10	0 → 100000	no	Interval in seconds at which to check for files that are inactive and close them.
mongodb_wterc_log_archive		categorical	true	true, false	no	Automatically archive unneeded log files.
mongodb_wterc_log_prealloc		categorical	false	true, false	no	Pre-allocate log files.
mongodb_wterc_log_zero_fill		categorical	true	true, false	no	Manually write zeroes into log files.
mongodb_wterc_lsm_manager_merge		categorical	true	true, false	no	Merge LSM chunks where possible.
mongodb_wterc_lsm_manager_worker_threads_max		integer	4	3 → 20	no	Configure a set of threads to manage merging LSM trees in the database.
mongodb_wterc_concurrent_read_transactions	transactions	integer	128	1 → 8192	no	Configure the number of concurrent read transactions allowed into the WiredTiger storage engine.
mongodb_wterc_concurrent_write_transactions	transactions	integer	128	1 → 8192	no	Configure the number of concurrent write transactions allowed into the WiredTiger storage engine.
mongodb_wterc_cursor_cache_size	cursors	integer	-100	-100000 → 100000	no	The absolute value of this parameter sets the maximum number of cursors cached at levels above the WiredTiger storage engine. Zero or negative values also enable the caching at the WiredTiger level.
mongodb_wterc_session_close_idle_time	seconds	integer	300	0 → 3600	no	Idle time in seconds before WiredTiger sessions are removed from the session cache.