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Fix the usage of parallel and full options of vacuum command.
author Amit Kapila <akapila@postgresql.org>
2020年4月16日 05:14:03 +0000 (10:44 +0530)
committer Amit Kapila <akapila@postgresql.org>
2020年4月16日 05:25:02 +0000 (10:55 +0530)
Earlier we were inconsistent in allowing the usage of parallel and
full options. Change it such that we disallow them only when they are
combined in a way that we don't support.

In passing, improve the comments in some of the existing tests of parallel
vacuum.

Reported-by: Tushar Ahuja
Author: Justin Pryzby, Amit Kapila
Reviewed-by: Sawada Masahiko, Michael Paquier, Mahendra Singh Thalor and
Amit Kapila
Discussion: https://postgr.es/m/58c8d171-e665-6fa3-a9d3-d9423b694dae%40enterprisedb.com

doc/src/sgml/ref/vacuum.sgml patch | blob | blame | history
src/backend/commands/vacuum.c patch | blob | blame | history
src/test/regress/expected/vacuum.out patch | blob | blame | history
src/test/regress/sql/vacuum.sql patch | blob | blame | history

diff --git a/doc/src/sgml/ref/vacuum.sgml b/doc/src/sgml/ref/vacuum.sgml
index 442977a50d5a074b521c0c6bb3d7564e4fd404f7..a48f75ad7baf28a0cd39903c89ad713ae7ebd972 100644 (file)
--- a/doc/src/sgml/ref/vacuum.sgml
+++ b/doc/src/sgml/ref/vacuum.sgml
@@ -235,22 +235,22 @@ VACUUM [ FULL ] [ FREEZE ] [ VERBOSE ] [ ANALYZE ] [ <replaceable class="paramet
Perform index vacuum and index cleanup phases of <command>VACUUM</command>
in parallel using <replaceable class="parameter">integer</replaceable>
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 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
- be used during execution. It is possible for a vacuum to run with fewer
- 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 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.
+ refer to <xref linkend="vacuum-phases"/>). In plain <command>VACUUM</command>
+ (without <literal>FULL</literal>), if the <literal>PARALLEL</literal> option
+ is omitted, then the number of workers is determined based on the number of
+ indexes on the relation that support parallel vacuum operation 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 be used during
+ execution. It is possible for a vacuum to run with fewer 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 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>
</listitem>
</varlistentry>
diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c
index 495ac23a26bd43db911132d20c9ffbd2c91fa803..5a110edb072ca2df40e866c0ce8e2ac9ec5801bf 100644 (file)
--- a/src/backend/commands/vacuum.c
+++ b/src/backend/commands/vacuum.c
@@ -104,7 +104,6 @@ ExecVacuum(ParseState *pstate, VacuumStmt *vacstmt, bool isTopLevel)
bool freeze = false;
bool full = false;
bool disable_page_skipping = false;
- bool parallel_option = false;
ListCell *lc;
/* Set default value */
@@ -145,7 +144,6 @@ ExecVacuum(ParseState *pstate, VacuumStmt *vacstmt, bool isTopLevel)
params.truncate = get_vacopt_ternary_value(opt);
else if (strcmp(opt->defname, "parallel") == 0)
{
- parallel_option = true;
if (opt->arg == NULL)
{
ereport(ERROR,
@@ -199,10 +197,10 @@ ExecVacuum(ParseState *pstate, VacuumStmt *vacstmt, bool isTopLevel)
!(params.options & (VACOPT_FULL | VACOPT_FREEZE)));
Assert(!(params.options & VACOPT_SKIPTOAST));
- if ((params.options & VACOPT_FULL) && parallel_option)
+ if ((params.options & VACOPT_FULL) && params.nworkers > 0)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
- errmsg("cannot specify both FULL and PARALLEL options")));
+ errmsg("VACUUM FULL cannot be performed in parallel")));
/*
* Make sure VACOPT_ANALYZE is specified if any column lists are present.
diff --git a/src/test/regress/expected/vacuum.out b/src/test/regress/expected/vacuum.out
index 0cfe28e63f6ec8cf4a4d1ef4ffb55b2497b55ac1..736c2f60d20f0486048f48ee3a8b0b48337922cb 100644 (file)
--- a/src/test/regress/expected/vacuum.out
+++ b/src/test/regress/expected/vacuum.out
@@ -115,15 +115,17 @@ LINE 1: VACUUM (PARALLEL -1) pvactst;
^
VACUUM (PARALLEL 2, INDEX_CLEANUP FALSE) pvactst;
VACUUM (PARALLEL 2, FULL TRUE) pvactst; -- error, cannot use both PARALLEL and FULL
-ERROR: cannot specify both FULL and PARALLEL options
+ERROR: VACUUM FULL cannot be performed in parallel
VACUUM (PARALLEL) pvactst; -- error, cannot use PARALLEL option without parallel degree
ERROR: parallel option requires a value between 0 and 1024
LINE 1: VACUUM (PARALLEL) pvactst;
^
+-- Test different combinations of parallel and full options for temporary tables
CREATE TEMPORARY TABLE tmp (a int PRIMARY KEY);
CREATE INDEX tmp_idx1 ON tmp (a);
-VACUUM (PARALLEL 1) tmp; -- disables parallel vacuum option
+VACUUM (PARALLEL 1, FULL FALSE) tmp; -- parallel vacuum disabled for temp tables
WARNING: disabling parallel option of vacuum on "tmp" --- cannot vacuum temporary tables in parallel
+VACUUM (PARALLEL 0, FULL TRUE) tmp; -- can specify parallel disabled (even though that's implied by FULL)
RESET min_parallel_index_scan_size;
DROP TABLE pvactst;
-- INDEX_CLEANUP option
diff --git a/src/test/regress/sql/vacuum.sql b/src/test/regress/sql/vacuum.sql
index cf741f7b114bb8fb74a488cf9d018834e29b005f..84dee8c8169e164e00916906052d223390922b36 100644 (file)
--- a/src/test/regress/sql/vacuum.sql
+++ b/src/test/regress/sql/vacuum.sql
@@ -100,9 +100,12 @@ VACUUM (PARALLEL -1) pvactst; -- error
VACUUM (PARALLEL 2, INDEX_CLEANUP FALSE) pvactst;
VACUUM (PARALLEL 2, FULL TRUE) pvactst; -- error, cannot use both PARALLEL and FULL
VACUUM (PARALLEL) pvactst; -- error, cannot use PARALLEL option without parallel degree
+
+-- Test different combinations of parallel and full options for temporary tables
CREATE TEMPORARY TABLE tmp (a int PRIMARY KEY);
CREATE INDEX tmp_idx1 ON tmp (a);
-VACUUM (PARALLEL 1) tmp; -- disables parallel vacuum option
+VACUUM (PARALLEL 1, FULL FALSE) tmp; -- parallel vacuum disabled for temp tables
+VACUUM (PARALLEL 0, FULL TRUE) tmp; -- can specify parallel disabled (even though that's implied by FULL)
RESET min_parallel_index_scan_size;
DROP TABLE pvactst;
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