Release Notes for MongoDB 7.1

7.1.1 - Nov 27, 2023

Issues fixed:

• SERVER-81106 Recipient shard doesn't wait for the collection version to be locally persisted before starting the cloning phase

• SERVER-81133 Speedup logic to persist routing table cache

• SERVER-81201 Limiting the memory usage during the cloning phase on the recipient shard

• SERVER-81966 Avoid modification of previous ChunkMap instances during refresh

• WT-7929 Investigate a solution to avoid FTDC stalls during checkpoint

• All JIRA issues closed in 7.1.1

• 7.1.1 Changelog

New Aggregation Stages

MongoDB 7.1 introduces the following aggregation stages:

Concurrent DDL Operations

Starting in MongoDB 7.1, when you run multiple DDL operations that target different collections from the same database, MongoDB runs those operations concurrently.

This change adds two new types to the serverStatus locks field and currentOp.locks output:

• DDLDatabase

• DDLCollection

Exhaust Cursors Enabled for Sharded Clusters

Starting in MongoDB 7.1, mongos supports exhaust cursors when a client's getMore request sets the exhaustAllowed flag. This can improve query performance on sharded clusters when the client receives multiple replies from the database server for a single request.

Improved Index Builds

Starting in MongoDB 7.1, index builds are improved with faster error reporting and increased failure resilience. You can also set the minimum available disk space required for index builds using the new indexBuildMinAvailableDiskSpaceMB parameter, which stops index builds if disk space is too low.

The following new index build metrics were added:

• indexBuilds.killedDueToInsufficientDiskSpace

• indexBuilds.failedDueToDataCorruption

For full details, see Index Builds.

New Sharding Statistics for Chunk Migrations

Available starting in MongoDB 7.1 (and 7.0, 6.3.2, 6.0.6, and 5.0.18).

MongoDB includes the following new sharding statistics for chunk migrations:

• shardingStatistics.countDonorMoveChunkCommitted

• shardingStatistics.countDonorMoveChunkAborted

• shardingStatistics.totalDonorMoveChunkTimeMillis

• shardingStatistics.countBytesClonedOnRecipient

• shardingStatistics.countDocsClonedOnCatchUpOnRecipient

• shardingStatistics.countBytesClonedOnCatchUpOnRecipient

Self-Managed Backups of Sharded Clusters

Starting in MongoDB 7.1, the fsync and fsyncUnlock commands can perform fsync operations on sharded clusters.

When run on mongos with the lock field set to true, the fsync command flushes writes from the storage layer to disk and locks each shard, preventing additional writes. The fsyncUnlock command can then be used to unlock the cluster.

This feature enables self-managed backups of sharded clusters using mongodump.

New Parameters

Query with Partial Shard Key

Starting in MongoDB 7.1, findAndModify and deleteOne() can use a partial shard key to query on a sharded collection.

mongos Port Range

Starting in MongoDB 7.1, mongos accepts --port values from [0, 65535]. For more information, see --port.

Specify a query's index using the hint field

Starting in MongoDB 7.1, the hint field is available in the distinct command, allowing you to specify the query's index.

TTL Indexes

Starting in MongoDB 7.1, you can create TTL indexes on capped collections.

Error Codes for Exceeding Pipeline Size Limit

Starting in MongoDB 7.1, an aggregation command will throw an error when a pipeline exceeds the pipeline stage limit. For more details, see Number of Stages Restrictions.