MongoDB 4

This page describes the Optimization Pack for MongoDb version 4.x.

Metrics

Document operations

Name	Unit	Description
mongodb_document_deleted	documents/s	The average number of documents deleted per second
mongodb_documents_inserted	documents/s	The average number of documents inserted per second
mongodb_documents_updated	documents/s	The average number of documents updated per second
mongodb_documents_returned	documents/s	The average number of documents returned by queries per second

Other metrics

Name	Unit	Description
mongodb_connections_current	connections	The current number of opened connections
mongodb_heap_used	bytes	The total size of heap space used (only available in Linux/Unix systems)
mongodb_mem_used	bytes	The total amount of memory used
mongodb_page_faults_total	faults/s	The average number of page faults per second (i.e., operations that require MongoDB to access data on disk rather than on memory)
mongodb_global_lock_current_queue	ops	The current number of operations queued because of a lock

Parameters

Cache

Name	Unit	Type	Default	Domain	Restart	Description
mongodb_cache_size	megabytes	Integer	You should select your own default value when you create a study, since it is highly dependent on your system (how much memory your system has)	You should select your own default value when you create a study, since it is highly dependent on your system (how much memory your system has)	No	The maximum size of the internal cache that MongoDB (WiredTiger) will use to operate
mongodb_eviction_trigger	percentage	Integer	95	1 → 99	No	The percentage threshold on the use of the MongoDB cache for which cache eviction will start and client threads will throttle
mongodb_eviction_target	percentage	Integer	80	1 → 99	No	The target percentage usage of the MongoDB cache to reach after evictions
mongodb_eviction_dirty_trigger	percentage	Integer	20	1 → 99	No	The percentage threshold on the use of MongoDB dirty cache for which cache eviction will start and client threads will throttle
mongodb_eviction_dirty_target	percentage	Integer	5	1 → 99	No	The target percentage usage of the MongoDB dirty cache to reach after evictions
mongodb_eviction_threads_min	threads	Integer	4	1 → 20	No	The minimum number of threads to use to perform cache eviction
mongodb_eviction_threads_max	threads	Integer	4	1 → 20	No	The maximum number of threads to use to perform cache eviction

Other parameters

Name	Unit	Type	Default	Domain	Restart	Description
mongodb_sync_delay	seconds	Integer	1min	1min → 6min	no	The temporal interval between fsync operations where mongod flushes its working memory to disk

Constraints

Here are some constraints on parameters of MongoDB 4 that avoid common errors in the configuration of a MongoDB deployment:

Constraint
mongodb_eviction_threads_min <= mongodb_eviction_threads_max
mongodb_eviction_dirty_target <= mongodb_eviction_target
mongodb_eviction_dirty_trigger <= mongodb_eviction_trigger