Release Notes for MongoDB 8.3

serverStatus Output

Starting in MongoDB 8.3, you can exclude all optional fields from the serverStatus output by specifying none: 1. After you exclude all optional fields, you can then specify the fields you want to include.

For details, see Exclude All Optional Fields.

String Conversion Enhancements

Starting in MongoDB 8.3, $toString can convert additional BSON types to strings, including objects, arrays, regular expressions, MaxKeys, MinKeys, and timestamps. For details, see $toString.

findShardsOnConfigTimeoutMS Parameter

MongoDB 8.3 adds the findShardsOnConfigTimeoutMS parameter which sets the timeout in milliseconds for find operations against the config.shards namespace. For details, see findShardsOnConfigTimeoutMS.

config.csrs.indexes Removed

MongoDB 8.3 removes the config.csrs.indexes namespace.

Time Series

Starting in MongoDB 8.3, creating an index with the name of "_id_" or specifying a hint of "_id_" on time series collections returns an error.

Fields to Track Use of Memory by Queries

Starting in MongoDB 8.3, you can use the following new fields to track query memory use:

Both fields appear in the following places:

• $currentOp (aggregation stage) output

• db.currentOp() output

• Database profiler output

• Log messages

• Slow query log messages

The peakTrackedMemBytes field also appears in the following places:

• Explain results

• PlanCache.list() output

• $planCacheStats output

cachePressureQueryPeriodMilliseconds Parameter

MongoDB 8.3 adds the cachePressureQueryPeriodMilliseconds parameter which sets the time interval MongoDB waits between checks for storage engine cache pressure. If the storage engine is under cache pressure, MongoDB aborts the oldest transaction. For details, see cachePressureQueryPeriodMilliseconds.