Release Notes for MongoDB 6.0 (Stable Release)
On this page本页内容
- Patch Releases
- Aggregation
- Change Streams
- Cluster Administration
- Clustered Collections
- Indexes
- Installation
- Replica Sets
- Security
- Sharding
- Slot-Based Query Execution Engine
- Stable API
- Time Series Collections
- General Improvements
- Changes Affecting Compatibility
- Upgrade Procedures
- Downgrade Consideration
- Download
- Known Issues
- Report an Issue
This page describes changes and new features introduced in MongoDB 6.0.
MongoDB 6.0 is a Major Release, which means that it is supported for both MongoDB Atlas and on-premises deployments. MongoDB 6.0 includes changes introduced in MongoDB Rapid Releases 5.1, 5.2, and 5.3. This page describes changes introduced in those Rapid Releases and MongoDB 6.0.
To learn more about the differences between Major and Rapid releases, see MongoDB Versioning.
Past Release Limitations
Some past releases have critical issues. These releases are not recommended for production use. Use the latest available patch release version instead.
| Issue | Affected Versions |
|---|---|
SERVER-68511 | 6.0.0 |
| WT-10461 | 6.0.0 - 6.0.4 (ARM64 or POWER system architectures) |
| WT-10551 | 6.0.0 - 6.0.5 (Incremental backups on Ops Manager or Cloud Manager clusters) |
Patch Releases
6.0.8 - Jul 13, 2023
- SERVER-61127 Multi-writes may exhaust the number of retry attempts in the presence of ongoing chunk migrations
- SERVER-77005 Leave LDAP users logged-in during LDAP downtime
- SERVER-78126 For specific kinds of input, mongo::Value() always hashes to the same result on big-endian platforms
- All Jira issues closed in 6.0.8
- 6.0.8 Changelog
6.0.7 - Jun 28, 2023
- SERVER-71985 Automatically retry time series insert on DuplicateKey error
- SERVER-73007 CURL_OPT_SEEKFUNCTION not set for multi-pass authentication
- SERVER-74551 WriteConflictException unnecessarily logged as warning during findAndModify after upgrade to mongo 5.0
- SERVER-77018 Deadlock between dbStats and 2 index builds
- WT-10449 Do not save update chain when there are no updates to be written to the history store
- WT-11031 Fix RTS to skip tables with no time window information in the checkpoint
- All Jira issues closed in 6.0.7
- 6.0.7 Changelog
6.0.6 - May 12, 2023
- SERVER-51835 Mongos readPreferenceTags are not working as expected
- SERVER-67105 $in queries do not use clustered index
- SERVER-72774 A node in quiesce mode can win election
- SERVER-74930 $avg is returning the sum instead of the average in aggregate $group
- SERVER-75205 Deadlock between stepdown and restoring locks after yielding when all read tickets exhausted
- All Jira issues closed in 6.0.6
- 6.0.6 Changelog
6.0.5 - Mar 13, 2023
Issues Fixed:
- SERVER-61909 Hang inserting or deleting document with large number of index entries
- SERVER-66469 Filtering timeseries with date-field does not include results from before 1970
- SERVER-68122 Investigate replicating the collection WiredTiger config string during initial sync
- SERVER-70395 Slot-Based Engine too aggressively uses disk for $group and is slow
- SERVER-73232 Change the default log-verbosity for
_killOperations - All JIRA issues closed in 6.0.5
- 6.0.5 Changelog
6.0.4 - Jan 26, 2023
Issues Fixed:
- SERVER-72416 The find and findAndModify projection code does not honor the collection level collation
- SERVER-71759
dataSizecommand doesn't yield - SERVER-70237 Chunks merge commit must not create a BSON object too large
- SERVER-72222
mapReducewith single reduce optimization fails when merging results in sharded cluster - WT-9268 Delay deletion of the history store record to reconciliation
- All JIRA issues closed in 6.0.4
- 6.0.4 Changelog
6.0.3 - Nov 21, 2022
Issues fixed:
- SERVER-66289 $out incorrectly throws BSONObj size error on v5.0.8
- SERVER-68139 Resharding command fails if the projection sort is bigger than 100MB
- SERVER-68371 Enabling CSFLE in your MongoClient causes Atlas Search to fail
- SERVER-68115 Bug fix for "elemMatchRootLength > 0" invariant trigger
- SERVER-68394 Ensure we do not yield strong locks upon startup recovery when _id index is missing
- All JIRA issues closed in 6.0.3
- 6.0.3 Changelog
6.0.2 - Sep 28, 2022
Issues fixed:
- SERVER-68925 Reintroduce check table logging settings at startup (revert SERVER-43664)
- SERVER-68628 Retrying a failed resharding operation after a primary failover can lead to server crash or lost writes
- SERVER-63852 getThreadName() should not crash
- SERVER-65317 mongod removes connection from connection pool after running simple $search query
- SERVER-63843 Don't allow recursive doLog in synchronous signal handlers
- WT-9870 Fix updating pinned timestamp whenever oldest timestamp is updated during recovery
- All JIRA issues closed in 6.0.2
- 6.0.2 Changelog
6.0.1 - Aug 19, 2022
Issues fixed:
- SERVER-68511 MovePrimary update of
config.databasesentry must use dotted fields notation - SERVER-68062 Multi-stage aggregations that use $geoNear may violate constraints
- SERVER-66072 $match sampling and $group aggregation strange behavior
- SERVER-68130 AutoSplitVector could generate response bigger than BSONObjMaxUserSize
- SERVER-68209 Remove uassert that prevents
config.image_collectionentry from being invalidated - All JIRA issues closed in 6.0.1
- 6.0.1 Changelog
6.0.0 - Jul 19, 2022
The rest of this page describes changes and new features introduced in MongoDB 6.0.
Aggregation
New Aggregation Stages
MongoDB 6.0 introduces the following aggregation stages:
| Stage | Description |
|---|---|
$densify | Creates new documents in a sequence of documents where values in a specified field are missing. |
$documents | Returns literal documents from input expressions. |
$fill | Populates null and missing field values within documents.
|
$shardedDataDistribution | New in version 6.0.3: Provides size and data distribution information on sharded collections.
|
New Aggregation Operators
MongoDB 6.0 introduces the following aggregation operators:
| Operator | Description |
|---|---|
$bottom | Returns the bottom element within a group according to the specified sort order. |
$bottomN | Returns an aggregation of the bottom n elements within a group, according to the specified sort order. |
$firstN | Returns an aggregation of the first n elements within a group. Distinct from the $firstN array operator. |
$firstN (array operator) | Returns a specified number of elements from the beginning of an array. Distinct from the $firstN accumulator. |
$lastN | Returns an aggregation of the last n elements within a group. Distinct from the $lastN array operator. |
$lastN (array operator) | Returns a specified number of elements from the end of an array. Distinct from the $lastN accumulator. |
$linearFill | Fills null and missing fields in a window using linear interpolation based on surrounding field values.
|
$locf | Last observation carried forward. Sets values for null and missing fields in a window to the last non-null value for the field.
|
$maxN | Returns an aggregation of the n maximum valued elements within a group. Distinct from the $maxN array operator. |
$maxN (array operator) | Returns the n largest values in an array. Distinct from the $maxN accumulator. |
$minN | Returns an aggregation of the n minimum valued elements within a group. Distinct from the $minN array operator. |
$minN (array operator) | Returns the n smallest values in an array. Distinct from the $minN accumulator. |
$sortArray | Sorts an array based on its elements. |
$top | Returns the top element within a group according to the specified sort order. Distinct from the command top. |
$topN | Returns an aggregation of the top n elements within a group, according to the specified sort order. |
$tsIncrement | Returns the incrementing ordinal from a timestamp as a long.
|
$tsSecond | Returns the seconds from a timestamp as a long.
|
$lookup and $graphLookup with Sharded Collections
Starting in MongoDB 5.1, the $lookup and $graphLookup aggregation stages support sharded collections in the from parameter.
In previous versions of MongoDB, $lookup and $graphLookup only allowed for unsharded from collections.
Change Streams
Optimized Change Streams
Starting in MongoDB 5.1, change streams are optimized, providing more efficient resource utilization and faster execution of some aggregation pipeline stages.
wallTime Change Stream Output Field
Starting in MongoDB 6.0, the change stream output has a new wallTime field that contains the server date and time of the database operation.
Change Streams with Document Pre- and Post-Images
Starting in MongoDB 6.0, you can use change streams to output the version of a document before and after changes (the document pre- and post-images). For examples, see Change Streams with Document Pre- and Post-Images.
Change Stream Expanded Events
Starting in MongoDB 6.0, change streams can show additional change events for DDL operations, like creating indexes and dropping collections.
For more information, see Expanded Events.
Filters
Starting in MongoDB 6.0, whenever possible, match filters are applied to change streams earlier than in prior releases. This improves performance. However, when a filter is narrowly defined, an earlier match may cause an operation that succeeds in prior versions to fail in 6.0.
Cluster Administration
Cluster Server Parameters
Starting in MongoDB 6.0, you can use MongoDB Cluster Parameters to modify and retrieve configuration options for all nodes in a replica set or sharded cluster. You can use setClusterParameter to modify cluster-wide options and getClusterParameter to retrieve the value of a cluster parameter.
Connection Pool Parameters
Starting in MongoDB 6.0, you can use ShardingTaskExecutorPoolMinSizeForConfigServers and ShardingTaskExecutorPoolMaxSizeForConfigServers to set the minimum and maximum sharding TaskExecutor connection pool size for configuration servers.
changeStreamOptions Cluster Parameter
Starting in MongoDB 6.0, you can use changeStreamOptions to control the retention policy of change stream pre- and post-images.
internalSessionsReapThreshold Parameter
Starting in MongoDB 6.0, you can use the new internalSessionsReapThreshold parameter to set the session limit for internal session metadata deletion.
Multiple Arbiters Unsupported
Starting in MongoDB 5.3, support for multiple arbiters in a replica set is disabled by default. To enable support for multiple arbiters, start each node with the allowMultipleArbiters parameter.
Clustered Collections
Starting in MongoDB 5.3, you can create a collection with a clustered index. Collections created with a clustered index are called clustered collections.
To learn about the benefits compared to a normal collection, see Clustered Collections.
Indexes
Starting in MongoDB 5.1, you can use the collMod database command to add the expireAfterSeconds option to an existing single-field non-TTL index.
Starting in MongoDB 6.0, you can use the prepareUnique and unique options for the collMod command to convert an existing standard index to a unique index.
Partial Indexes
Starting in MongoDB 6.0, you can use the operators $in and $or to create partial indexes. The partialFilterExpression maximum depth is also expanded from 2 to 4. You can now use the operators $and and $or at non-top-levels.
Installation
SELinux Policies
Starting in MongoDB 5.1, there is a new SE Linux Policy for:
- MongoDB Enterprise Server
- MongoDB Community Edition Server
running on Red Hat Linux. The SELinux policy is for use with default installations using rpm installer packages.
Replica Sets
Multiple Arbiters Unsupported
Starting in MongoDB 5.3, support for multiple arbiters in a replica set is disabled by default. To enable support for multiple arbiters, start each node with the allowMultipleArbiters parameter.
initialSyncMethod Parameter
Starting in MongoDB 5.2, the initialSyncMethod determines whether initial sync is a logical initial sync or a file copy based initial sync.
initialSyncMethod is only available in MongoDB Enterprise Server.
Specify Secondary Oplog Batch Delay
Starting in MongoDB 6.0, you can use the oplogBatchDelayMillis server parameter to specify a delay for writes of oplog batches on secondaries. Adding a short oplog batch delay can reduce IOPS on secondaries, but adds latency for writes with write concern "majority".
For more information, see oplogBatchDelayMillis.
Security
Audit Log Encryption
Starting in MongoDB 6.0 Enterprise, you can encrypt the MongoDB audit log.
To configure the audit log, see Audit Log.
Sharding
Default Chunk Size Increased from 64 MB to 128 MB
Starting in MongoDB 5.2, the default chunk size is 128 megabytes. In earlier versions of MongoDB, the default chunk size is 64 megabytes.
enableSharding No Longer Required
Starting in MongoDB 6.0, the enableSharding command is no longer required to shard a collection.
Monitor Defragmentation Status
Starting in MongoDB 5.3, the balancerCollectionStatus command returns detailed information when run on a namespace going through chunk defragmentation. The output includes the current phase of the defragmentation and how many chunks are left to process.
To see example output, see Ongoing Defragmentation Process.
Slot-Based Query Execution Engine
Starting in MongoDB 5.1, MongoDB uses a new query execution engine for eligible queries, called the slot-based query execution engine. If the slot-based query execution engine is used, new fields are included in the query explain plan output.
- The new query execution engine is used if possible.
- If the new query execution engine is used, new fields are included in the query explain plan output.
Slot-Based Query Execution Engine Can Execute $group and $lookup Stages
Starting in version 6.0, MongoDB uses the slot-based query execution engine to execute eligible $group and $lookup stages when certain conditions are met.
For more information, see Slot-Based Query Execution Engine Pipeline Optimizations.
Set Slot-Based Query Execution Engine Plan Cache Size
You can set the size of the plan cache for the new query engine with the planCacheSize parameter.
Increasing the plan cache size adds more cached query shapes for the query planner. This can improve query performance, but increases memory usage.
Stable API
The following sections describe additions to the Stable API introduced in MongoDB 6.0.
To see the full list of database commands available in the Stable API, see Stable API Changelog.
Database Commands
Starting in MongoDB 6.0, the following database commands are supported in the Stable API:
| Command | Description | Stable API Version |
|---|---|---|
count | Counts the number of documents in a collection or a view. (Also available in the Stable API for 5.0-series deployments starting in MongoDB 5.0.9.) | V1 |
Aggregation Stages and Operators
Starting in MongoDB 6.0, the following aggregation stages and operators are supported in the Stable API:
| Stage or Operator | Description | Stable API Version |
|---|---|---|
$bottom | Returns the bottom element within a group, according to the specified sort order. | V1 |
$bottomN | Returns an aggregation of the bottom n elements within a group, according to the specified sort order. | V1 |
$dateAdd | Increments a Date() object by a specified number of time units. | V1 |
$dateDiff | Returns the difference between two dates. | V1 |
$dateSubtract | Decrements a Date() object by a specified number of time units. | V1 |
$dateTrunc | Truncates a date. | V1 |
$densify | Creates new documents in a sequence of documents where certain values in a field are missing. | V1 |
$firstN (aggregation accumulator) | Returns an aggregation of the first n elements within a group. | V1 |
$firstN (array operator) | Returns a specified number of elements from the beginning of an array. | V1 |
$getField | Returns the value of a specified field from a document. | V1 |
$lastN (aggregation accumulator) | Returns an aggregation of the last n elements within a group. | V1 |
$lastN (array operator) | Returns a specified number of elements from the end of an array. | V1 |
$locf | Last observation carried forward. Sets values for null and missing fields in a window to the last non-null value for the field.
| V1 |
$maxN (aggregation accumulator) | Returns an aggregation of the maximum value n elements within a group. | V1 |
$maxN (array operator) | Returns the n largest values in an array. | V1 |
$minN (aggregation accumulator) | Returns an aggregation of the minimum value n elements within a group. | V1 |
$minN (array operator) | Returns the n smallest values in an array. | V1 |
$setField | Adds, updates, or removes a specified field in a document. | V1 |
$setWindowFields | Performs operations on a specified span of documents in a collection, known as a window, and returns the results based on the chosen window operator. | V1 |
$sortArray | Sorts an array based on its elements. | V1 |
$top | Returns the top element within a group according to the specified sort order. | V1 |
$topN | Returns an aggregation of the top n elements within a group, according to the specified sort order. | V1 |
$tsIncrement | Returns the incrementing ordinal from a timestamp as a long.
| V1 |
$tsSecond | Returns the seconds from a timestamp as a long.
| V1 |
Window Operators
Starting in MongoDB 6.0, the following window operators are supported in the Stable API:
| Window Operator | Description | Stable API Version |
|---|---|---|
$addToSet | Returns an array of all unique values that results from applying an expression to each document. | V1 |
$avg | Returns the average for the specified expression. Ignores non-numeric values. | V1 |
$count | Returns the number of documents in the group or window. | V1 |
$covariancePop | Returns the population covariance of two numeric expressions. | V1 |
$covarianceSamp | Returns the sample covariance of two numeric expressions. | V1 |
$denseRank | Returns the document position (known as the rank) relative to other documents in the $setWindowFields stage partition. There are no gaps in the ranks. Ties receive the same rank. | V1 |
$derivative | Returns the average rate of change within the specified window. | V1 |
$documentNumber | Returns the position of a document (known as the document number) in the $setWindowFields stage partition. Ties result in different adjacent document numbers. | V1 |
$expMovingAvg | Returns the exponential moving average for the numeric expression. | V1 |
$first | Returns the value that results from applying an expression to the first document in a group or window. | V1 |
$integral | Returns the approximation of the area under a curve. | V1 |
$last | Returns the value that results from applying an expression to the last document in a group or window. | V1 |
$locf | Last observation carried forward. Sets values for null and missing fields in a window to the last non-null value for the field.
| V1 |
$max | Returns the maximum value that results from applying an expression to each document. | V1 |
$min | Returns the minimum value that results from applying an expression to each document. | V1 |
$push | Returns an array of values that result from applying an expression to each document. | V1 |
$rank | Returns the document position (known as the rank) relative to other documents in the $setWindowFields stage partition. | V1 |
$shift | Returns the value from an expression applied to a document in a specified position relative to the current document in the $setWindowFields stage partition. | V1 |
$stdDevPop | Returns the population standard deviation that results from applying a numeric expression to each document. | V1 |
$stdDevSamp | Returns the sample standard deviation that results from applying a numeric expression to each document. | V1 |
$sum | Returns the sum that results from applying a numeric expression to each document. | V1 |
Time Series Collections
The following sections describe improvements and new features for time series collections.
Sharded Time Series Collections
MongoDB 5.1 provides support for sharded time series collections.
See:
Sharded Time Series Granularity
Starting in MongoDB 6.0, you can modify the granularity of sharded time series collections.
Updates and Deletes
Starting in MongoDB 5.1, time series collections support update and delete operations with limitations.
Time Series Column Compression
Starting in MongoDB 5.2, time series collections use column compression. Column compression adds a number of innovations that work together to significantly improve practical compression, reduce your data's overall storage on disk, and improve read performance.
Starting in MongoDB 6.0, arrays are also compressed as part of the time series column compression.
Support for $geoNear
Starting in MongoDB 5.3, you can use the $geoNear pipeline operator on any field in a time series collection.
Additional Secondary Index Types
You can add additional secondary index types to time series collections, including 2dsphere and 2d indexes.
For all additional indexes and other improvements, see Time Series Secondary Indexes in MongoDB 6.0 and Later.
Sort Operations Use Secondary Indexes
Sort operations on time series collections can use indexes to improve performance. For more information and an example, see Use Secondary Indexes to Improve Sort Performance.
General Improvements
OpenSSL3 FIPS Support
Starting in MongoDB 6.0.7, FIPS mode supports OpenSSL3 for the following operating systems:
- Ubuntu 22.04
- RHEL 9
- Amazon Linux 2023
Capped Collections Improvements
Starting in MongoDB 6.0, you can change a capped collection's maximum size, either in bytes or in number of documents, using the collMod command. See Resize a Capped Collection for more details.
numOrphanDocs Field Added to collStats Command
Starting in MongoDB 6.0, the collStats output includes the collStats.numOrphanDocs field that shows the number of orphaned documents in the collection.
Exclude Embedded Fields in serverStatus Output
Starting in MongoDB 6.0 (and 5.0.9, 4.4.15), you can exclude embedded fields from the serverStatus output.
Connections
Starting in MongoDB 6.0, the Mongo() connection object has the following new methods:
Mongo.getWriteConcern()returns the write concernMongo.setWriteConcern()sets the write concern
Support for Diagnostic Backtrace Generation in arm64
Starting in MongoDB 6.0 (and 5.0.10, 4.4.15), diagnostic backtrace generation in arm64 is supported.
Configure Refresh Interval for Cached LDAP User Information
Starting in MongoDB 5.2, you can use the following new server parameters to configure the refresh interval for cached LDAP user information:
Starting in MongoDB 5.2, the update interval for cached user information retrieved from an LDAP server depends on ldapShouldRefreshUserCacheEntries:
- If true, use
ldapUserCacheRefreshInterval. - If false, use
ldapUserCacheInvalidationInterval.
Changes Affecting Compatibility
Some changes can affect compatibility and may require user actions. For a detailed list of compatibility changes, see Compatibility Changes in MongoDB 6.0.
Upgrade Procedures
Feature Compatibility Version
To upgrade to MongoDB 6.0 from a 5.0 deployment, the 5.0 deployment must have featureCompatibilityVersion set to 5.0. To check the version:
db.adminCommand( { getParameter: 1, featureCompatibilityVersion: 1 } )
To upgrade to MongoDB 6.0, refer to the upgrade instructions specific to your MongoDB deployment:
If you need guidance on upgrading to 6.0, MongoDB professional services offer major version upgrade support to help ensure a smooth transition without interruption to your MongoDB application. To learn more, see MongoDB Consulting.
Downgrade Consideration
MongoDB only supports single-version downgrades. You cannot downgrade to a release that is multiple versions behind your current release.
For example, you may downgrade a 6.0-series to a 5.0-series deployment. However, further downgrading that 5.0-series deployment to a 4.4-series deployment is not supported.
Download
To download MongoDB 6.0, go to the MongoDB Download Center.
Known Issues
This section describes known issues in MongoDB 6.0 and their resolution status.
| In Version | Issue | Status |
|---|---|---|
| 6.0.0 | SERVER-68062: Multi-stage aggregations that use $geoNear may violate constraints. | Resolved in 6.0.1. |
Report an Issue
To report an issue, see the MongoDB GitHub repository for instructions on how to file a JIRA ticket for the MongoDB server or one of the related projects.