Kernel parameter release notes
Lists kernel parameter changes for ApsaraDB for MongoDB, including new, modified, and removed parameters.
For the supported parameters, see List of Supported MongoDB Parameters.
2026
May 2026
|
Type |
Parameter |
Versions |
Description |
|
new |
setParameter.periodicNoopIntervalSecs |
4.2 4.4 5.0 6.0 7.0 8.0 |
Specifies the interval, in seconds, for periodic noop writes. |
January 2026
|
Type |
Parameter |
Versions |
Description |
|
new |
setParameter.internalDocumentSourceGroupMaxMemoryBytes |
4.2 4.4 5.0 6.0 7.0 8.0 |
Limits the maximum memory the $group operator can use. Data that exceeds this limit spills to disk. |
|
setParameter.readHedgingMode |
4.4 5.0 6.0 7.0 8.0 |
Enables or disables hedged reads. |
|
|
setParameter.taskExecutorPoolSize |
7.0 8.0 |
Sets the number of TaskExecutor connection pools on a mongos process. Note
Supported only in baseline versions 7.0.26 and later, and 8.0.13 and later. |
|
|
modified |
setParameter.taskExecutorPoolSize |
4.2 4.4 5.0 6.0 |
Sets the number of TaskExecutor connection pools on a mongos process. The update behavior for this parameter changed from no restart required to requires restart. |
|
removed |
setParameter.chunkMigrationConcurrency |
5.0 6.0 7.0 8.0 |
Sets the concurrency level (number of threads) for chunk migration. Reason for removal: Extensive testing showed that increasing this parameter does not improve chunk migration speed. Instead, it can place excessive pressure on the RangeDeleter. MongoDB deprecated this parameter in major version 7.0. For more information, see SERVER-95324. |
2025
November 2025
|
Type |
Parameter |
Affected versions |
Description |
|
New |
setParameter.internalQueryMaxPushBytes |
4.2 4.4 5.0 6.0 7.0 8.0 |
Limits the maximum memory that the $push operator can use. |
|
setParameter.internalQueryMaxAddToSetBytes |
Limits the maximum memory that the $addToSet operator can use. |
||
|
setParameter.internalDocumentSourceCursorBatchSizeBytes |
Sets the maximum data in bytes that a DocumentSourceCursor can cache from the underlying PlanExecutor before pipeline processing. |
||
|
Modified |
setParameter.internalQueryMaxBlockingSortMemoryUsageBytes |
4.4 5.0 6.0 7.0 8.0 |
Sets the maximum memory in bytes that a blocking sort stage can use during a query. The default value is 100 MB. |
|
New |
setParameter.internalQueryCacheSize |
4.2 4.4 |
Limits the maximum number of entries in the query plan cache for a collection. The default value is 5,000. |
|
setParameter.internalQueryCacheMaxEntriesPerCollection |
5.0 6.0 7.0 8.0 |
July 2025
|
Type |
Parameter |
Affected versions |
Description |
|
New |
setParameter.timeseriesBucketMaxCount |
8.0 |
Sets the maximum number of measurements in a bucket for a time-series collection. |
|
setParameter.timeseriesIdleBucketExpiryMemoryUsageThreshold |
8.0 |
Sets the memory threshold at which idle buckets in a time-series collection are expired. |
|
|
setParameter.timeseriesSideBucketCatalogMemoryUsageThreshold |
8.0 |
Sets the memory threshold for the side bucket catalog in a time-series collection, above which idle buckets are expired. |
April 2025
MongoDB 8.0 adds support for new parameters. For details, see List of Parameters for MongoDB 8.0.
March 2025
|
Type |
Parameter |
Affected versions |
Description |
|
Modified |
operationProfiling.mode |
4.2 4.4 5.0 6.0 7.0 |
Specifies the database profiler level. The update behavior for this parameter has changed from no restart required to restart required. |
|
New |
rsconf.chainingAllowed |
4.0 4.2 4.4 5.0 6.0 7.0 |
Determines whether to allow chained replication in a replica set. |
February 2025
|
Type |
Parameter |
Affected versions |
Description |
|
New |
setParameter.timeseriesBucketMaxCount |
5.0 6.0 7.0 |
Sets the maximum number of measurements in a bucket for a time-series collection. |
|
setParameter.timeseriesIdleBucketExpiryMemoryUsageThreshold |
6.0 7.0 |
Sets the memory threshold at which idle buckets in a time-series collection are expired. |
2024
December 2024
|
Type |
Parameter |
Affected versions |
Description |
|
new |
setParameter.chunkMigrationConcurrency |
5.0 7.0 |
Specifies the concurrency (number of threads) for chunk migration. |
|
setParameter.receiveChunkWaitForRangeDeleterTimeoutMS |
4.4 5.0 6.0 7.0 |
Specifies the timeout for deleting orphaned documents before a chunk migration. |
|
|
setParameter.maxTargetSnapshotHistoryWindowInSeconds |
4.4 |
Specifies the window size for retaining snapshot history in the WT engine. |
|
|
setParameter.minSnapshotHistoryWindowInSeconds |
5.0 6.0 7.0 |
July 2024
|
Type |
Parameter |
Affected versions |
Description |
|
new |
replication.oplogGlobalIdEnabled |
6.0 |
Controls whether oplog GID is enabled for bidirectional synchronization. |
April 2024
The following parameters now support mongos in sharded cluster instances.
|
Type |
Parameter |
Affected versions |
Description |
|
new |
operationProfiling.slowOpThresholdMs |
4.2 4.4 5.0 6.0 7.0 |
The time threshold, in milliseconds, that an operation must exceed to be considered slow. |
|
setParameter.tcmallocReleaseRate |
Specifies the rate at which TCMalloc releases memory to the OS; a higher value indicates a faster rate. |
||
|
setParameter.tcmallocAggressiveMemoryDecommit |
Specifies whether to enable aggressive memory decommitment for TCMalloc. |
February 2024
The update behavior for the following parameters has been changed from requires restart to no restart required.
|
Type |
Parameter |
Affected versions |
Description |
|
modified |
setParameter.ShardingTaskExecutorPoolMaxSize |
4.4 7.0 6.0 7.0 5.0 6.0 7.0 |
The maximum number of connections in each TaskExecutor connection pool for a sharded cluster instance. |
|
setParameter.rangeDeleterBatchDelayMS |
The interval between batch deletions during the cleanup step of a chunk migration. This also affects the |
||
|
setParameter.rangeDeleterBatchSize |
The maximum number of documents in a single batch for asynchronous deletion during the cleanup step of a chunk migration. |
||
|
setParameter.ShardingTaskExecutorPoolMinSize |
The minimum number of connections in each TaskExecutor connection pool for a sharded cluster instance. |
||
|
setParameter.cursorTimeoutMillis |
The timeout for an idle cursor. |
||
|
setParameter.tcmallocAggressiveMemoryDecommit |
Specifies whether to enable aggressive memory decommitment for TCMalloc. |
||
|
setParameter.ShardingTaskExecutorPoolHostTimeoutMS |
The timeout before mongos closes all connections to a host's TaskExecutor connection pool. |
||
|
setParameter.migrateCloneInsertionBatchSize |
The maximum number of documents in a single batch during the clone step of a chunk migration. |
||
|
setParameter.maxTransactionLockRequestTimeoutMillis |
The timeout for acquiring locks for a transaction. |
||
|
operationProfiling.slowOpThresholdMs |
The time threshold, in milliseconds, that an operation must exceed to be considered slow. |
||
|
setParameter.transactionLifetimeLimitSeconds |
The maximum lifetime of a transaction. |
||
|
setParameter.taskExecutorPoolSize |
The number of TaskExecutor connection pools on mongos. This parameter has no effect on Linux systems. |
||
|
setParameter.ShardingTaskExecutorPoolMaxConnecting |
The maximum concurrency for initializing connections in the TaskExecutor connection pool of a sharded cluster instance. |
||
|
setParameter.ShardingTaskExecutorPoolRefreshRequirementMS |
The interval at which mongos sends heartbeats to idle connections in the TaskExecutor connection pool. |
||
|
setParameter.ShardingTaskExecutorPoolRefreshTimeoutMS |
The timeout for a heartbeat response. |
||
|
replication.oplogSizeMB |
The maximum size of the oplog. |
||
|
setParameter.flowControlTargetLagSeconds |
The replication lag threshold that triggers flow control. Flow control ensures that most commit points do not lag significantly. |
||
|
rsconf.writeConcernMajorityJournalDefault |
4.2 4.4 5.0 6.0 7.0 |
Controls whether writes with a "majority" write concern also require persistence to the journal. |
January 2024
MongoDB 7.0 is available. For a list of parameters supported in this version, see List of available parameters for MongoDB 7.0.