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Comments and doc fixes for commit 40d964ec99.

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Reported-by: Justin Pryzby
Author: Justin Pryzby, with few changes by me
Reviewed-by: Amit Kapila and Sawada Masahiko
Discussion: https://postgr.es/m/20200322021801.GB2563@telsasoft.com
This commit is contained in:
Amit Kapila
2020-04-14 08:10:27 +05:30
parent 826ee1a019
commit a6fea120a7
5 changed files with 49 additions and 49 deletions
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22
doc/src/sgml/ref/vacuum.sgml
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@ -232,15 +232,15 @@ VACUUM [ FULL ] [ FREEZE ] [ VERBOSE ] [ ANALYZE ] [ <replaceable class="paramet
<term><literal>PARALLEL</literal></term>
<listitem>
<para>
Perform vacuum index and cleanup index phases of <command>VACUUM</command>
Perform index vacuum and index cleanup phases of <command>VACUUM</command>
in parallel using <replaceable class="parameter">integer</replaceable>
background workers (for the detail of each vacuum phases, please
background workers (for the details of each vacuum phase, please
refer to <xref linkend="vacuum-phases"/>). If the
<literal>PARALLEL</literal> option is omitted, then
<command>VACUUM</command> decides the number of workers based on number
of indexes that support parallel vacuum operation on the relation which
is further limited by <xref linkend="guc-max-parallel-workers-maintenance"/>.
The index can participate in a parallel vacuum if and only if the size
<literal>PARALLEL</literal> option is omitted, then the number of workers
is determined based on the number of indexes that support parallel vacuum
operation on the relation, and is further limited by <xref
linkend="guc-max-parallel-workers-maintenance"/>.
An index can participate in parallel vacuum if and only if the size
of the index is more than <xref linkend="guc-min-parallel-index-scan-size"/>.
Please note that it is not guaranteed that the number of parallel workers
specified in <replaceable class="parameter">integer</replaceable> will
@ -248,7 +248,7 @@ VACUUM [ FULL ] [ FREEZE ] [ VERBOSE ] [ ANALYZE ] [ <replaceable class="paramet
workers than specified, or even with no workers at all. Only one worker
can be used per index. So parallel workers are launched only when there
are at least <literal>2</literal> indexes in the table. Workers for
vacuum launches before starting each phase and exit at the end of
vacuum are launched before the start of each phase and exit at the end of
the phase. These behaviors might change in a future release. This
option can't be used with the <literal>FULL</literal> option.
</para>
@ -358,8 +358,8 @@ VACUUM [ FULL ] [ FREEZE ] [ VERBOSE ] [ ANALYZE ] [ <replaceable class="paramet
</para>
<para>
The <option>PARALLEL</option> option is used only for vacuum purpose.
Even if this option is specified with <option>ANALYZE</option> option
The <option>PARALLEL</option> option is used only for vacuum purposes.
If this option is specified with the <option>ANALYZE</option> option,
it does not affect <option>ANALYZE</option>.
</para>
@ -367,7 +367,7 @@ VACUUM [ FULL ] [ FREEZE ] [ VERBOSE ] [ ANALYZE ] [ <replaceable class="paramet
<command>VACUUM</command> causes a substantial increase in I/O traffic,
which might cause poor performance for other active sessions. Therefore,
it is sometimes advisable to use the cost-based vacuum delay feature. For
parallel vacuum, each worker sleeps proportional to the work done by that
parallel vacuum, each worker sleeps in proportion to the work done by that
worker. See <xref linkend="runtime-config-resource-vacuum-cost"/> for
details.
</para>