The PostgreSQL Global Development Group has released an update to all supported versions of our database system, including 9.6.2, 9.5.6, 9.4.11, 9.3.16, and 9.2.20. This release includes fixes that prevent data corruption issues in index builds and in certain write-ahead-log replay situations, which are detailed below. It also patches over 75 other bugs reported over the last three months.
Users should plan to apply this update at the next scheduled downtime.
There existed a race condition if CREATE INDEX CONCURRENTLY was called on a column that had not been indexed before, then rows that were updated by transactions running at the same time as the CREATE INDEX CONCURRENTLY command could have been indexed incorrectly.
If you suspect this may have happened, the most reliable solution is to rebuild affected indexes after installing this update.
This issue is present in the 9.2, 9.3, 9.4, 9.5, and 9.6 series of PostgreSQL.
This release contains several fixes to improve the stability of visible data and WAL logging that we wish to highlight here.
Prior to this release, data could be prematurely pruned by a vacuum operation when a special snapshot used for catalog scans was presently available. Specifically, the vacuum operation would not be aware of the oldest xmin for this special snapshot. The error would surface with a message such as:
"cache lookup failed for relation 1255"
This release ensures that vacuum operations will account for the catalog scan snapshots.
Additionally, there are several fixes to improved the stability of write-ahead-logging, including:
These issues are present in the 9.6 series of PostgreSQL releases and may also be present in the 9.2, 9.3, 9.4, and 9.5 series.
This update also fixes a number of bugs reported in the last few months. Some of these issues affect only the 9.6 series, but many affect all supported versions. There are more than 75 fixes provided in this release, including:
Update time zone data files to tzdata release 2016j for DST law changes in northern Cyprus (adding a new zone Asia/Famagusta), Russia (adding a new zone Europe/Saratov), Tonga, and Antarctica/Casey. Historical corrections for Italy, Kazakhstan, Malta, and Palestine. Switch to preferring numeric zone abbreviations for Tonga.
All PostgreSQL update releases are cumulative. 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.
If you believe you have been affected by the aforementioned CREATE INDEX CONCURRENTLY bug, you will have to rebuild the index. Here is an example of how to rebuild an index in a production system without losing the ability to utilize the index:
CREATE INDEX CONCURRENTLY new_index_name ON table_name (column_name); DROP INDEX CONCURRENTLY old_index_name; ALTER INDEX new_index_name RENAME TO old_index_name;
Note that using this method means you will briefly have two copies of the same index, so if disk space is an issue you may need to take other approaches.
Users who have skipped one or more update releases may need to run additional, post-update steps; please see the release notes for earlier versions for details.