Doc: Add relfrozenxid Tip to XID wraparound section.

petergeoghegan · petergeoghegan · commit 05023a237c05 · 2022-04-02T13:34:57.000-07:00
VACUUM VERBOSE and autovacuum log reports were taught to report the details of how VACUUM advanced relfrozenxid (and relminmxid) by commit 872770f. Highlight this by adding a "Tip" to the documentation, next to related discussion of age(relfrozenxid) monitoring. Author: Peter Geoghegan <pg@bowt.ie> Discussion: https://postgr.es/m/CAH2-Wzk0C1O-MKkOrj4YAfsGRru2=cA2VQpqM-9R1HNuG3nFaQ@mail.gmail.com
diff --git a/doc/src/sgml/maintenance.sgml b/doc/src/sgml/maintenance.sgml
@@ -611,6 +611,19 @@ SELECT datname, age(datfrozenxid) FROM pg_database;
     cutoff XID to the current transaction's XID.
    </para>
 
+   <tip>
+    <para>
+     When the <command>VACUUM</command> command's <literal>VERBOSE</literal>
+     parameter is specified, <command>VACUUM</command> prints various
+     statistics about the table.  This includes information about how
+     <structfield>relfrozenxid</structfield> and
+     <structfield>relminmxid</structfield> advanced.  The same details appear
+     in the server log when autovacuum logging (controlled by <xref
+      linkend="guc-log-autovacuum-min-duration"/>) reports on a
+     <command>VACUUM</command> operation executed by autovacuum.
+    </para>
+   </tip>
+
    <para>
     <command>VACUUM</command> normally only scans pages that have been modified
     since the last vacuum, but <structfield>relfrozenxid</structfield> can only be
