autovacuum_freeze_max_age

doc html

<p>
         Specifies the maximum age (in transactions) that a table's
         <code class="structname">pg_class</code>.<code class="structfield">relfrozenxid</code> field can
         attain before a <code class="command">VACUUM</code> operation is forced
         to prevent transaction ID wraparound within the table.
         Note that the system will launch autovacuum processes to
         prevent wraparound even when autovacuum is otherwise disabled.
        </p><p>
         Vacuum also allows removal of old files from the
         <code class="filename">pg_xact</code> subdirectory, which is why the default
         is a relatively low 200 million transactions.
         This parameter can only be set at server start, but the setting
         can be reduced for individual tables by
         changing table storage parameters.
         For more information see <a class="xref" href="/docs/18/routine-vacuuming.html#VACUUM-FOR-WRAPAROUND" title="24.1.5. Preventing Transaction ID Wraparound Failures">Section 24.1.5</a>.
        </p>

documentation revision

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