diff options
author | Amit Kapila | 2020-04-14 02:40:27 +0000 |
---|---|---|
committer | Amit Kapila | 2020-04-14 02:40:27 +0000 |
commit | a6fea120a7e3858e642bb5e96027f166a1a6f134 (patch) | |
tree | 6dc527a06a5a8f437ec06eb52edc45157e73a111 /doc/src/sgml/ref/vacuum.sgml | |
parent | 826ee1a019127d611bb0fd22ca878142bfb077ac (diff) |
Comments and doc fixes for commit 40d964ec99.
Reported-by: Justin Pryzby
Author: Justin Pryzby, with few changes by me
Reviewed-by: Amit Kapila and Sawada Masahiko
Discussion: https://postgr.es/m/[email protected]
Diffstat (limited to 'doc/src/sgml/ref/vacuum.sgml')
-rw-r--r-- | doc/src/sgml/ref/vacuum.sgml | 22 |
1 files changed, 11 insertions, 11 deletions
diff --git a/doc/src/sgml/ref/vacuum.sgml b/doc/src/sgml/ref/vacuum.sgml index 846056a353d..442977a50d5 100644 --- a/doc/src/sgml/ref/vacuum.sgml +++ b/doc/src/sgml/ref/vacuum.sgml @@ -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> |