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| -rw-r--r-- | doc/src/sgml/maintenance.sgml | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/doc/src/sgml/maintenance.sgml b/doc/src/sgml/maintenance.sgml index 16ed9b4d5fd..08bdf7c4252 100644 --- a/doc/src/sgml/maintenance.sgml +++ b/doc/src/sgml/maintenance.sgml @@ -808,6 +808,26 @@ analyze threshold = analyze base threshold + analyze scale factor * number of tu <literal>autovacuum_vacuum_cost_limit</> storage parameters have been set are not considered in the balancing algorithm. </para> + + <para> + Autovacuum workers generally don't block other commands. If a process + attempts to acquire a lock that conficts with the + <literal>SHARE UPDATE EXCLUSIVE</literal> lock held by autovacuum, lock + acquisition will interrupt the autovacuum. For conflicting lock modes, + see <xref linkend="table-lock-compatibility">. However, if the autovacuum + is running to prevent transaction ID wraparound (i.e., the autovacuum query + name in the <structname>pg_stat_activity</structname> view ends with + <literal>(to prevent wraparound)</literal>), the autovacuum is not + automatically interrupted. + </para> + + <warning> + <para> + Regularly running commands that acquire locks conflicting with a + <literal>SHARE UPDATE EXCLUSIVE</literal> lock (e.g., ANALYZE) can + effectively prevent autovacuums from ever completing. + </para> + </warning> </sect2> </sect1> |