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authorMichael Paquier <michael@paquier.xyz>2021-04-22 09:47:43 +0900
committerMichael Paquier <michael@paquier.xyz>2021-04-22 09:47:43 +0900
commit1599e7b375127cac81b539d2c69d3faf7598509b (patch)
tree00d56eac4c3b1405d12f55c3763e9167aeb85917
parent7c298c6573a0f181963ddcb40c850fa9c7da0ada (diff)
downloadpostgresql-1599e7b375127cac81b539d2c69d3faf7598509b.tar.gz
postgresql-1599e7b375127cac81b539d2c69d3faf7598509b.zip
doc: Move parallel_leader_participation to its correct category
parallel_leader_participation got introduced in e5253fd, where it was listed under RESOURCES_ASYNCHRONOUS in guc.c, but the documentation did not reflect that and listed it with the other planner-related options. This commit fixes this inconsistency as the parameter is intended to be an asynchronous one. While on it, reorganize a bit the section dedicated to asynchronous parameters, backend_flush_after being moved first to do better in terms of alphabetical order of the options listed. Reported-by: Yanliang Lei Author: Bharath Rupireddy Discussion: https://postgr.es/m/16972-42d4b0c15aa1d5f5@postgresql.org
-rw-r--r--doc/src/sgml/config.sgml88
1 files changed, 44 insertions, 44 deletions
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
index dd7ebe7a9da..cf75d913ce9 100644
--- a/doc/src/sgml/config.sgml
+++ b/doc/src/sgml/config.sgml
@@ -2383,6 +2383,36 @@ include_dir 'conf.d'
<title>Asynchronous Behavior</title>
<variablelist>
+ <varlistentry id="guc-backend-flush-after" xreflabel="backend_flush_after">
+ <term><varname>backend_flush_after</varname> (<type>integer</type>)
+ <indexterm>
+ <primary><varname>backend_flush_after</varname> configuration parameter</primary>
+ </indexterm>
+ </term>
+ <listitem>
+ <para>
+ Whenever more than this amount of data has
+ been written by a single backend, attempt to force the OS to issue
+ these writes to the underlying storage. Doing so will limit the
+ amount of dirty data in the kernel's page cache, reducing the
+ likelihood of stalls when an <function>fsync</function> is issued at the end of a
+ checkpoint, or when the OS writes data back in larger batches in the
+ background. Often that will result in greatly reduced transaction
+ latency, but there also are some cases, especially with workloads
+ that are bigger than <xref linkend="guc-shared-buffers"/>, but smaller
+ than the OS's page cache, where performance might degrade. This
+ setting may have no effect on some platforms.
+ If this value is specified without units, it is taken as blocks,
+ that is <symbol>BLCKSZ</symbol> bytes, typically 8kB.
+ The valid range is
+ between <literal>0</literal>, which disables forced writeback,
+ and <literal>2MB</literal>. The default is <literal>0</literal>, i.e., no
+ forced writeback. (If <symbol>BLCKSZ</symbol> is not 8kB,
+ the maximum value scales proportionally to it.)
+ </para>
+ </listitem>
+ </varlistentry>
+
<varlistentry id="guc-effective-io-concurrency" xreflabel="effective_io_concurrency">
<term><varname>effective_io_concurrency</varname> (<type>integer</type>)
<indexterm>
@@ -2579,32 +2609,25 @@ include_dir 'conf.d'
</listitem>
</varlistentry>
- <varlistentry id="guc-backend-flush-after" xreflabel="backend_flush_after">
- <term><varname>backend_flush_after</varname> (<type>integer</type>)
+ <varlistentry id="guc-parallel-leader-participation" xreflabel="parallel_leader_participation">
+ <term>
+ <varname>parallel_leader_participation</varname> (<type>boolean</type>)
<indexterm>
- <primary><varname>backend_flush_after</varname> configuration parameter</primary>
+ <primary><varname>parallel_leader_participation</varname> configuration parameter</primary>
</indexterm>
</term>
<listitem>
<para>
- Whenever more than this amount of data has
- been written by a single backend, attempt to force the OS to issue
- these writes to the underlying storage. Doing so will limit the
- amount of dirty data in the kernel's page cache, reducing the
- likelihood of stalls when an <function>fsync</function> is issued at the end of a
- checkpoint, or when the OS writes data back in larger batches in the
- background. Often that will result in greatly reduced transaction
- latency, but there also are some cases, especially with workloads
- that are bigger than <xref linkend="guc-shared-buffers"/>, but smaller
- than the OS's page cache, where performance might degrade. This
- setting may have no effect on some platforms.
- If this value is specified without units, it is taken as blocks,
- that is <symbol>BLCKSZ</symbol> bytes, typically 8kB.
- The valid range is
- between <literal>0</literal>, which disables forced writeback,
- and <literal>2MB</literal>. The default is <literal>0</literal>, i.e., no
- forced writeback. (If <symbol>BLCKSZ</symbol> is not 8kB,
- the maximum value scales proportionally to it.)
+ Allows the leader process to execute the query plan under
+ <literal>Gather</literal> and <literal>Gather Merge</literal> nodes
+ instead of waiting for worker processes. The default is
+ <literal>on</literal>. Setting this value to <literal>off</literal>
+ reduces the likelihood that workers will become blocked because the
+ leader is not reading tuples fast enough, but requires the leader
+ process to wait for worker processes to start up before the first
+ tuples can be produced. The degree to which the leader can help or
+ hinder performance depends on the plan type, number of workers and
+ query duration.
</para>
</listitem>
</varlistentry>
@@ -5889,29 +5912,6 @@ SELECT * FROM parent WHERE key = 2400;
</listitem>
</varlistentry>
- <varlistentry id="guc-parallel-leader-participation" xreflabel="parallel_leader_participation">
- <term>
- <varname>parallel_leader_participation</varname> (<type>boolean</type>)
- <indexterm>
- <primary><varname>parallel_leader_participation</varname> configuration parameter</primary>
- </indexterm>
- </term>
- <listitem>
- <para>
- Allows the leader process to execute the query plan under
- <literal>Gather</literal> and <literal>Gather Merge</literal> nodes
- instead of waiting for worker processes. The default is
- <literal>on</literal>. Setting this value to <literal>off</literal>
- reduces the likelihood that workers will become blocked because the
- leader is not reading tuples fast enough, but requires the leader
- process to wait for worker processes to start up before the first
- tuples can be produced. The degree to which the leader can help or
- hinder performance depends on the plan type, number of workers and
- query duration.
- </para>
- </listitem>
- </varlistentry>
-
<varlistentry id="guc-plan-cache_mode" xreflabel="plan_cache_mode">
<term><varname>plan_cache_mode</varname> (<type>enum</type>)
<indexterm>