The update fixes two potential data corruption issues present in the PostgreSQL 9.1 and 9.2 for any server which has crashed, been shutdown with "immediate", or was failed over to a standby. First, the PostgreSQL development team has discovered a chance of corruption of BTREE and GIN indexes for databases. Second, there is a significant chance of corruption of the visibility map. This update fixes both issues.
We strongly advise users of 9.1 and 9.2 to run VACUUM and/or index rebuilds after applying the update. Please see the 2012-09-24 Update wiki page for detailed instructions.
This update release also contains fixes for many minor issues discovered and patched by the PostgreSQL community in the last month, including many fixes for the newly released version 9.2. These include:
fix sorting issue with IN lists and indexes
fix planner failure when combining GROUP BY with window functions
improve selectivity of text searches using prefixes
prevent rescanning of WITH clauses from giving wrong answers
fix PL/Perl crashing issue
reduce bloat for multi-column GiST indexes
time zone data changes for Fiji
disallow Extensions from circular schema assignment
prevent crashes when default_transaction_isolation is set to "serializable"
several minor fixes to pg_upgrade