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:
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 | Type | Default | Domain | Restart | Description |
|---|---|---|---|---|---|---|
| Name | Unit | Type | Default | Domain | Restart | Description |
|---|---|---|---|---|---|---|
| Constraint |
|---|
| Name | Unit | Description |
|---|
| Name | Unit | Description |
|---|
| Name | Unit | Type | Default | Domain | Restart | Description |
|---|
MongoDB version 4.x
MongoDB version 5.x
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
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 |
|
| no | Return an error when executing queries that don't use indices. |
mongodb_ttlMonitorEnabled | categorical |
|
| no | Disable the TTL monitor works, preventing TTL documents removal |
mongodb_disableJavaScriptJIT | categorical |
|
| 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 |
|
| 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 |
|
| no | Automatically archive unneeded log files. |
mongodb_wterc_log_prealloc | categorical |
|
| no | Pre-allocate log files. |
mongodb_wterc_log_zero_fill | categorical |
|
| no | Manually write zeroes into log files. |
mongodb_wterc_lsm_manager_merge | categorical |
|
| 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. |