Hi team,
Attaching a proposed patch to make it more explicit that
max_parallel_maintenance_workers does not apply to autovacuum, which does not
use parallelism. I personally believe that this could be made clearer.
Sources of autovacuum not running parallelism:
1)
postgres/src/backend/postmaster/autovacuum.c, line 2913 at time of writing:
/* As of now, we don't support parallel vacuum for autovacuum */
2)
https://www.2ndquadrant.com/en/blog/parallelism-comes-to-vacuum/ - "Parallel
vacuum is always disabled in autovacuum.""
Best regards,
Matthew
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index f323bba018..6d03115d37 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -2663,7 +2663,7 @@ include_dir 'conf.d'
utility commands that support the use of parallel workers are
<command>CREATE INDEX</command> only when building a B-tree index,
and <command>VACUUM</command> without <literal>FULL</literal>
- option. Parallel workers are taken from the pool of processes
+ option. This parameter does not apply to autovacuum, which does not use parallelism. Parallel workers are taken from the pool of processes
established by <xref linkend="guc-max-worker-processes"/>, limited
by <xref linkend="guc-max-parallel-workers"/>. Note that the requested
number of workers may not actually be available at run time.
