Release Notes for MongoDB 3.0¶

3.0.15 – May 15, 2017¶

Issues fixed:

• SERVER-27164: Deadlock during initial sync or steady state replication when CRUD operations implicitly create collections on the same database.
• SERVER-28548: In MMAPv1, index readers/writers can return invalid data if record no longer exists.
• All issues closed in 3.0.15

3.0.14 – Nov 4, 2016¶

Issues fixed:

• Incorrect memory access on 3.0.13 triggers segmentation fault: SERVER-26889

3.0.13 – Oct 31, 2016¶

Issues fixed:

• Debian 8(Jessie) packages: SERVER-18329
• Upgrade to Perl compatible regular expressions (PCRE 8.39): SERVER-24662
• Limit memory usage during 2dsphere index build: SERVER-25075
• All issues closed in 3.0.13

3.0.12 – May 9, 2016¶

Issues fixed:

• Background index build may result in extra index key entries that do not correspond to indexed documents: SERVER-22970
• Documents that contain embedded null characters can be created: SERVER-7005
• IX GlobalLock being held while waiting for WiredTiger cache eviction: SERVER-22964
• All issues closed in 3.0.12

3.0.11 – Mar 31, 2016¶

Issues fixed:

• For MongoDB 3.0.9 and MongoDB 3.0.10, during chunk migration, insert and update operations to documents in the migrating chunk are not reflected in the destination shard: SERVER-23425

3.0.10 – Mar 8, 2016¶

Issues fixed:

• Read preference of secondaryPreferred can end up using unversioned connections: SERVER-18671
• For MMAPv1 journaling, the “last sequence number” file (lsn file) may be ahead of what is synced to the data files: SERVER-22261.
• Data size change for oplog deletes can overflow 32-bit int: SERVER-22634
• High fragmentation on WiredTiger databases under write workloads: SERVER-22898.
• All issues closed in 3.0.10

3.0.9 – Jan 26, 2016¶

Issues fixed:

• Queries which specify sort and batch size can return results out of order if documents are concurrently updated. SERVER-19996
• Large amounts of create and drop collections can cause listDatabases to be slow under WiredTiger. SERVER-20961
• Authentication failure message includes server IP address instead of the client IP address. SERVER-22054
• All issues closed in 3.0.9

3.0.8 – Dec 15, 2015¶

Issues fixed:

• findAndModify on mongos can upsert to the wrong shard. SERVER-20407.
• WiredTiger commit visibility caused document not found. SERVER-21275.
• The oplog can grow to 3x configured size. SERVER-21553
• All issues closed in 3.0.8

3.0.7 – Oct 13, 2015¶

Issues fixed:

• WiredTiger memory handling and performance issues: SERVER-20159, SERVER-20204, SERVER-20091, and SERVER-20176.
• Reconfig during a pending step down may prevent a primary from stepping down: SERVER-20262.
• Built-in roles requires additional privileges: SERVER-19131, SERVER-15893, and SERVER-13647.
• All issues closed in 3.0.7

3.0.6 – August 24, 2015¶

Issues fixed:

• WiredTiger Stability issues: SERVER-19751, SERVER-19673, and SERVER-19573.
• Interaction between SSL and Auditing: SERVER-19538.
• Aggregation $sort on sharded systems SERVER-19464.
• All issues closed in 3.0.6

3.0.5 – July 28, 2015¶

Issues fixed and improvements:

• Improvements to WiredTiger for capped collections and replication (SERVER-19178, SERVER-18875 and SERVER-19513).
• Additional WiredTiger improvements for performance (SERVER-19189) and improvements related to cache and session use (SERVER-18829 SERVER-17836).
• Performance improvements for longer running queries, particularly $text and $near queries SERVER-18926.
• All issues closed in 3.0.5

3.0.4 – June 16, 2015¶

Issues fixed:

• Missed writes with concurrent inserts during chunk migration from shards with WiredTiger primaries: SERVER-18822
• Write conflicts with multi-update updates with upsert=true with the Wired Tiger Storage engine: SERVER-18213
• Secondary reads could block replication: SERVER-18190
• Performance on Windows with WiredTiger and documents larger than 16kb: SERVER-18079
• WiredTiger data files are not correctly recovered following unexpected system restarts: SERVER-18316
• All issues closed in 3.0.4

3.0.3 – May 12, 2015¶

Issues fixed:

• Deprecate db.eval() and add warnings: SERVER-17453
• Potential for abrupt termination with the Windows service stop operation: SERVER-17802
• Crash caused by update with a key too large to index on WiredTiger and RocksDB storage engines: SERVER-17882
• Inconsistent support for mapReduce in eval environment: SERVER-17889
• All issues closed in 3.0.3

3.0.2 – April 9, 2015¶

Issues fixed:

• Inefficient query plans for 2d $nearSphere: SERVER-17469
• Starting mongod during repair operations with WiredTiger: SERVER-17652 and SERVER-17729
• Invalid compression stream error with WiredTiger and zlib block compression: SERVER-17713
• Memory use issue for inserts into large indexed arrays: SERVER-17616
• All issues closed in 3.0.2

3.0.1 – March 17, 2015¶

Issues fixed:

• Race condition in WiredTiger between inserts and checkpoints that could result in lost records: SERVER-17506.
• WiredTiger’s capped collections implementation causes a server crash: SERVER-17345.
• Initial sync with duplicate _id entries: SERVER-17487.
• Deadlock condition in MMAPv1 between the journal lock and the oplog collection lock: SERVER-17416.
• All issues closed in 3.0.1

Pluggable Storage Engine API¶

MongoDB 3.0 introduces a pluggable storage engine API that allows third parties to develop storage engines for MongoDB.

WiredTiger¶

MongoDB 3.0 introduces support for the WiredTiger storage engine. With the support for WiredTiger, MongoDB now supports two storage engines:

• MMAPv1, the storage engine available in previous versions of MongoDB and the default storage engine for MongoDB 3.0, and
• WiredTiger, available only in the 64-bit versions of MongoDB 3.0.

MMAPv1 Improvements¶

Increased Number of Replica Set Members¶

In MongoDB 3.0, replica sets can have up to 50 members. [1] The following drivers support the larger replica sets:

• C# (.NET) Driver 1.10
• Java Driver 2.13
• Python Driver (PyMongo) 3.0
• Ruby Driver 2.0
• Node.JS Driver 2.0

The C, C++, Perl, and legacy PHP drivers, as well as the earlier versions of the Ruby, Python, and Node.JS drivers, discover and monitor replica set members serially, and thus are not suitable for use with large replica sets.

Replica Set Step Down Behavior Changes¶

The process that a primary member of a replica set uses to step down has the following changes:

• Before stepping down, replSetStepDown will attempt to terminate long running user operations that would block the primary from stepping down, such as an index build, a write operation or a map-reduce job.
• To help prevent rollbacks, the replSetStepDown will wait for an electable secondary to catch up to the state of the primary before stepping down. Previously, a primary would wait for a secondary to catch up to within 10 seconds of the primary (i.e. a secondary with a replication lag of 10 seconds or less) before stepping down.
• replSetStepDown now allows users to specify a secondaryCatchUpPeriodSecs parameter to specify how long the primary should wait for a secondary to catch up before stepping down.

Other Replica Set Operational Changes¶

• Initial sync builds indexes more efficiently for each collection and applies oplog entries in batches using threads.
• Definition of w: “majority” write concern changed to mean majority of voting nodes.
• Stronger restrictions on Replica Set Configuration. For details, see Replica Set Configuration Validation.
• For pre-existing collections on secondary members, MongoDB 3.0 no longer automatically builds missing _id indexes.

New Query Introspection System¶

MongoDB 3.0 includes a new query introspection system that provides an improved output format and a finer-grained introspection into both query plan and query execution.

For details, see the new db.collection.explain() method and the new explain command as well as the updated cursor.explain() method.

For information on the format of the new output, see Explain Results.

Enhanced Logging¶

To improve usability of the log messages for diagnosis, MongoDB categorizes some log messages under specific components, or operations, and provides the ability to set the verbosity level for these components. For information, see Log Messages.

MongoDB Tools Enhancements¶

All MongoDB tools except for mongosniff and mongoperf are now written in Go and maintained as a separate project.

• New options for parallelized mongodump and mongorestore. You can control the number of collections that mongorestore will restore at a time with the --numParallelCollections option.
• New options -excludeCollection and --excludeCollectionsWithPrefix for mongodump to exclude collections.
• mongorestore can now accept BSON data input from standard input in addition to reading BSON data from file.
• mongostat and mongotop can now return output in JSON format with the --json option.
• Added configurable write concern to mongoimport, mongorestore, and mongofiles. Use the --writeConcern option. The default writeConcern has been changed to ‘w:majority’.
• mongofiles now allows you to configure the GridFS prefix with the --prefix option so that you can use custom namespaces and store multiple GridFS namespaces in a single database.

Indexes¶

• Background index builds will no longer automatically interrupt if dropDatabase, drop, dropIndexes operations occur for the database or collection affected by the index builds. The dropDatabase, drop, and dropIndexes commands will still fail with the error message a background operation is currently running, as in 2.6.
• If you specify multiple indexes to the createIndexes command,
  • the command only scans the collection once, and
  • if at least one index is to be built in the foreground, the operation will build all the specified indexes in the foreground.
• For sharded collections, indexes can now cover queries that execute against the mongos if the index includes the shard key.

Query Enhancements¶

MongoDB 3.0 includes the following query enhancements:

• For geospatial queries, adds support for “big” polygons for $geoIntersects and $geoWithin queries. “Big” polygons are single-ringed GeoJSON polygons with areas greater than that of a single hemisphere. See $geometry, $geoIntersects, and $geoWithin for details.
• For aggregate(), adds a new $dateToString operator to facilitate converting a date to a formatted string.
• Adds the $eq query operator to query for equality conditions.

Distributions and Supported Versions¶

Most non-Enterprise MongoDB distributions now include support for TLS/SSL. Previously, only MongoDB Enterprise distributions came with TLS/SSL support included; for non-Enterprise distributions, you had to build MongoDB locally with the --ssl flag (i.e. scons --ssl).

32-bit MongoDB builds are available for testing, but are not for production use. 32-bit MongoDB builds do not include the WiredTiger storage engine.

MongoDB builds for Solaris do not support the WiredTiger storage engine.

MongoDB builds are available for Windows Server 2003 and Windows Vista (as “64-bit Legacy”), but the minimum officially supported Windows version is Windows Server 2008.

Package Repositories¶

Non-Enterprise MongoDB Linux packages for 3.0 and later are in a new repository. Follow the appropriate Linux installation instructions to install the 3.0 packages from the new location.

Auditing¶

Auditing in MongoDB Enterprise can filter on any field in the audit message, including the fields returned in the param document. This enhancement, along with the auditAuthorizationSuccess parameter, enables auditing to filter on CRUD operations. However, enabling auditAuthorizationSuccess to audit of all authorization successes degrades performance more than auditing only the authorization failures.

Changes Affecting Compatibility¶

Some changes in 3.0 can affect compatibility and may require user actions. For a detailed list of compatibility changes, see Compatibility Changes in MongoDB 3.0.

Upgrade Process¶

See Upgrade MongoDB to 3.0 for full upgrade instructions.

Download¶

To download MongoDB 3.0, go to the downloads page.