vacuum_multixact_failsafe_age

doc html

<p>
         Specifies the maximum age (in multixacts) that a table's
         <code class="structname">pg_class</code>.<code class="structfield">relminmxid</code>
         field can attain before <code class="command">VACUUM</code> takes
         extraordinary measures to avoid system-wide multixact ID
         wraparound failure.  This is <code class="command">VACUUM</code>'s
         strategy of last resort.  The failsafe typically triggers when
         an autovacuum to prevent transaction ID wraparound has already
         been running for some time, though it's possible for the
         failsafe to trigger during any <code class="command">VACUUM</code>.
        </p><p>
         When the failsafe is triggered, any cost-based delay that is
         in effect will no longer be applied, and further non-essential
         maintenance tasks (such as index vacuuming) are bypassed.
        </p><p>
         The default is 1.6 billion multixacts.  Although users can set
         this value anywhere from zero to 2.1 billion,
         <code class="command">VACUUM</code> will silently adjust the effective
         value to no less than 105% of <a class="xref" href="/docs/18/runtime-config-vacuum.html#GUC-AUTOVACUUM-MULTIXACT-FREEZE-MAX-AGE">autovacuum_multixact_freeze_max_age</a>.
        </p>

documentation revision

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