E.48.1. Migration to Version 8.4.21

A dump/restore is not required for those running 8.4.X.

However, if you are upgrading from a version earlier than 8.4.19, see Section E.50.

E.48.2. Changes

• Restore GIN metapages unconditionally to avoid torn-page risk (Heikki Linnakangas)

  Although this oversight could theoretically result in a corrupted index, it is unlikely to have caused any problems in practice, since the active part of a GIN metapage is smaller than a standard 512-byte disk sector.

• Allow regular-expression operators to be terminated early by query cancel requests (Tom Lane)

  This prevents scenarios wherein a pathological regular expression could lock up a server process uninterruptably for a long time.

• Remove incorrect code that tried to allow OVERLAPS with single-element row arguments (Joshua Yanovski)

  This code never worked correctly, and since the case is neither specified by the SQL standard nor documented, it seemed better to remove it than fix it.

• Avoid getting more than AccessShareLock when de-parsing a rule or view (Dean Rasheed)

  This oversight resulted in pg_dump unexpectedly acquiring RowExclusiveLock locks on tables mentioned as the targets of INSERT/UPDATE/DELETE commands in rules. While usually harmless, that could interfere with concurrent transactions that tried to acquire, for example, ShareLock on those tables.

• Prevent interrupts while reporting non-ERROR messages (Tom Lane)

  This guards against rare server-process freezeups due to recursive entry to syslog(), and perhaps other related problems.

• Update time zone data files to tzdata release 2014a for DST law changes in Fiji and Turkey, plus historical changes in Israel and Ukraine.