The PostgreSQL Global Development Group has released a critical update to all supported versions of the PostgreSQL database system, which includes minor versions 9.3.2, 9.2.6, 9.1.11, 9.0.15, and 8.4.19. This update fixes three serious data-loss bugs affecting replication and database maintenance. All users are urged to update their installations at the earliest opportunity.
The replication issue affects some users of PostgreSQL binary replication, and can cause minor data loss between the master and the standby. While not all users are affected, it is difficult to predict when the bug will occur, so we urge all users of replication and continuous backup (PITR) to update immediately. Additionally, users who had replication running under PostgreSQL minor versions 9.3.0, 9.3.1, 9.2.5, 9.1.10, or 9.0.14 should plan to take a fresh base backup of each standby after update, in order to ensure no prior data corruption already exists. More information about this issue is on its wiki page.
This release also fixes two timing issues with VACUUM, which can cause old, overwritten or deleted rows to re-appear at a later date under some circumstances. Users with very high transaction rates, particularly those who experience "transaction ID wraparound" every few weeks or less, are the most at risk for this issue. Those users should set vacuum_freeze_table_age to 0, and run a database-wide VACUUM after the update. The second of the two VACUUM issues affects only 9.3, making it expecially important for 9.3 users to update.
Additional fixes included in this release, some of which only affect version 9.3, include:
Additional changes and details of some of the above issues can be found in the Release Notes.
As with other minor releases, users are not required to dump and reload their database or use pg_upgrade in order to apply this update release; you may simply shut down PostgreSQL and update its binaries. Users who have skipped multiple update releases may need to perform additional post-update steps; see the Release Notes for details.