diff options
| author | Robert Haas <rhaas@postgresql.org> | 2016-12-02 07:42:58 -0500 |
|---|---|---|
| committer | Robert Haas <rhaas@postgresql.org> | 2016-12-02 07:42:58 -0500 |
| commit | b460f5d6693103076dc554aa7cbb96e1e53074f9 (patch) | |
| tree | 01fd17d21facc8d329936fb18ec554d41c39abf7 /doc/src | |
| parent | 5714931b075b2dc8994b6e464ea3845c33ecf416 (diff) | |
Add max_parallel_workers GUC.
Increase the default value of the existing max_worker_processes GUC
from 8 to 16, and add a new max_parallel_workers GUC with a maximum
of 8. This way, even if the maximum amount of parallel query is
happening, there is still room for background workers that do other
things, as originally envisioned when max_worker_processes was added.
Julien Rouhaud, reviewed by Amit Kapila and by revised by me.
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/config.sgml | 23 |
1 files changed, 20 insertions, 3 deletions
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index b1c5289fccc..fdf8b3e9c77 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -1982,7 +1982,7 @@ include_dir 'conf.d' <para> Sets the maximum number of background processes that the system can support. This parameter can only be set at server start. The - default is 8. + default is 16. </para> <para> @@ -2004,8 +2004,9 @@ include_dir 'conf.d' Sets the maximum number of workers that can be started by a single <literal>Gather</literal> node. Parallel workers are taken from the pool of processes established by - <xref linkend="guc-max-worker-processes">. Note that the requested - number of workers may not actually be available at run time. If this + <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 runtime. If this occurs, the plan will run with fewer workers than expected, which may be inefficient. The default value is 2. Setting this value to 0 disables parallel query execution. @@ -2034,6 +2035,22 @@ include_dir 'conf.d' </listitem> </varlistentry> + <varlistentry id="guc-max-parallel-workers" xreflabel="max_parallel_workers"> + <term><varname>max_parallel_workers</varname> (<type>integer</type>) + <indexterm> + <primary><varname>max_parallel_workers</> configuration parameter</primary> + </indexterm> + </term> + <listitem> + <para> + Sets the maximum number of workers that the system can support for + parallel queries. The default value is 8. When increasing or + decreasing this value, consider also adjusting + <xref linkend="guc-max-parallel-workers-per-gather">. + </para> + </listitem> + </varlistentry> + <varlistentry id="guc-backend-flush-after" xreflabel="backend_flush_after"> <term><varname>backend_flush_after</varname> (<type>integer</type>) <indexterm> |