MongoDB Documentation, Release 3.0.4 See JavaScript Changes in MongoDB 2.4 (page 885) for more information about all changes . Enable basic BSON object validation for mongod and mongorestore when writing to MongoDB data files. See wireObjectCheck for details. BSON Document Validation Enabled by Default for mongod and mongorestore Index Build Enhancements • Add support for multiple concurrent index builds in the background by a single mongod instance. See building indexes in the background (page 508) for more information on background index builds. • Allow the db.killOp() method to terminate a foreground index build. • Improve index validation during index creation. See Compatibility and Index Type Changes in MongoDB 2.4 (page 899) for more information. Set Parameters as Command Line Options Changed Replication Behavior for Chunk Migration Improved Chunk Migration Queue Behavior Enterprise SASL Library Change Provide --setParameter as a command line option for mongos and mongod . See mongod and mongos for list of available options for setParameter . By default, each document move during chunk migration (page 685) in a sharded cluster propagates to at least one secondary before the balancer proceeds with its next operation. See Chunk Migration and Replication (page 687). Increase performance for moving multiple chunks off an overloaded shard. The balancer no longer waits for the current migration’s delete phase to complete before starting the next chunk migration. See Chunk Migration Queuing (page 686) for details. The following changes are specific to MongoDB Enterprise Editions: In 2.4.4, MongoDB Enterprise uses Cyrus SASL. Earlier 2.4 Enterprise versions use GNU SASL ( libgsasl ). To upgrade to 2.4.4 MongoDB Enterprise or greater, you must install all package dependencies related to this change, including the appropriate Cyrus SASL GSSAPI library. See Install MongoDB Enterprise (page 33) for details of the dependencies. 12.2. Previous Stable Releases 891