Comment 19 for bug 1257211

This bug was fixed in the package postgresql-8.4 - 8.4.19-0ubuntu0.12.04

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postgresql-8.4 (8.4.19-0ubuntu0.12.04) precise-proposed; urgency=low

  * New upstream bug fix release (LP: #1257211)
    - Fix "VACUUM"'s tests to see whether it can update relfrozenxid.
      In some cases "VACUUM" (either manual or autovacuum) could
      incorrectly advance a table's relfrozenxid value, allowing tuples
      to escape freezing, causing those rows to become invisible once
      2^31 transactions have elapsed. The probability of data loss is
      fairly low since multiple incorrect advancements would need to
      happen before actual loss occurs, but it's not zero. Users
      upgrading from release 8.4.8 or earlier are not affected, but all
      later versions contain the bug.
      The issue can be ameliorated by, after upgrading, vacuuming all
      tables in all databases while having vacuum_freeze_table_age set to
      zero. This will fix any latent corruption but will not be able to
      fix all pre-existing data errors. However, an installation can be
      presumed safe after performing this vacuuming if it has executed
      fewer than 2^31 update transactions in its lifetime (check this
      with SELECT txid_current() < 2^31).
    - See HISTORY/changelog.gz for details about bug fixes.
 -- Martin Pitt <email address hidden> Tue, 03 Dec 2013 10:44:58 +0100