General

• This release is focused on bug fixes since 1.4.0.

New features and improvements

• Improved the speed and reduced the impact of deletes after a chunk migration. (#957)
• Improved the speed of the touch command. (#959)
• TokuMX now gathers more information and tries to output it to the log on a crash. (#987, #993)
• Added compressionRatio section to serverStatus to report the compression ratio calculated on disk write. (#989)
• Added aggregate per-index stats in output of db.collection.stats() for sharded collections. (#1019)

Bug fixes

• Newly sharded databases now have their primary shard chosen as the most lightly loaded shard (by data size), rather than always choosing the first shard. (#422, #1029)
• Fixed the output of show dbs and listDatabases in sharded clusters. (#962)
• Fixed a bad query plan used by a secondary to find its rollback point in the oplog, which could cause startup to time out. (#965)
• Removed erroneous system.namespaces entries for partitioned collections, including the oplog. (#966, #967)
• Enabled the use of a hashed shard key when there is a user-defined primary key. In 1.4.0, the shard key would be rejected because the primary key looks like a unique index whose uniqueness cannot be enforced, however, for a primary key it is enforced by the _id's uniqueness assumption. (#968)
• Fixed linking of some commands, including loadPlugin and the bulk loader commands in mongorestore. (#977, #981, #983)
• Fixed problem opening too many files on startup, causing listening sockets' ids to be too high. (#978, #984)
• Changing storage settings (compression, page sizes, etc.) with reIndex now correctly persists the change for future opens and added partitions. (#982)
• The getParameter command now accepts journalCommitInterval as an alias for logFlushPeriod. (#988)
• Fixed issue with listDatabases and partitioned collections. (#997)
• Fixed a race between aborting a transaction due to client disconnect, and the transaction abort due to replica set relinquish. (#1003)
• Fixed the way errors during chunk migration cleanup are handled to avoid a crash when a replica set primary steps down at the end of a migration. (#1010)
• Fixed an issue that could cause migrations to fail repeatedly. (#1011)
• Fixed command authorization settings for enterprise plugin loading commands. (#1012)
• Fixed a bug that caused migrations to fail when the migration causes the recipient shard to transition an index to multiKey. (#1025)
• Backported a fix for SERVER-12515, a bug that corrupts the state of the config.chunks collection in sharded clusters when using hashed shard keys. (#1030)