The MongoDB optimization pack helps you optimize instances of MongoDB to reach the desired performance goal. The optimization pack provides parameters and metrics specific to MongoDB that can be leveraged to reach, among others, two main goals:
Throughput optimization - increasing the capacity of a MongoDB deployment to serve clients
Cost optimization - decreasing the size of a MongoDB deployment while guaranteeing the same service level
To reach such goals the pack focuses mostly on the parameters managing the cache, being one of the elements that impact performances the most; in particular, the optimization pack provides parameters to control the lifecycle and the size of the MongoDB’s cache thus significantly impacting performance.
Even though it is possible to evaluate performance improvements of MongoDB by looking at the business application that uses it as its database, looking at the end to end throughput or response time or using a performance test like YCSB, the optimization pack provides internal MongoDB metrics that can shed a light too on how MongoDB is performing, in particular in terms of throughput, for example:
The number of documents inserted in the database per second
The number of active connections
The optimization pack supports the following version of MongoDB.
| Component Type | Description |
|---|---|
Here’s the command to install the MongoDB optimization-pack using the Akamas CLI:
MongoDB version 4.x
MongoDB version 5.x
This page describes the Optimization Pack for MongoDb version 4.x.
| Name | Unit | Description |
|---|---|---|
| Name | Unit | Description |
|---|---|---|
Here are some constraints on parameters of MongoDB 4 that avoid common errors in the configuration of a MongoDB deployment:
| Name | Unit | Description |
|---|---|---|
| Name | Unit | Description |
|---|---|---|
| Name | Unit | Type | Default | Domain | Restart | Description |
|---|---|---|---|---|---|---|
| Name | Unit | Type | Default | Domain | Restart | Description |
|---|---|---|---|---|---|---|
| Name | Unit | Type | Default | Domain | Restart | Description |
|---|---|---|---|---|---|---|
| Constraint |
|---|
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.
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.
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.
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.
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.
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
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
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
mongodb_sync_delay
seconds
Integer
1min
1min → 6min
no
The temporal interval between fsync operations where mongod flushes its working memory to disk
mongodb_eviction_threads_min <= mongodb_eviction_threads_max
mongodb_eviction_dirty_target <= mongodb_eviction_target
mongodb_eviction_dirty_trigger <= mongodb_eviction_trigger