On Wed, Mar 19, 2025 at 10:40:31AM -0500, Nathan Bossart wrote: > On Thu, Mar 20, 2025 at 12:34:59AM +0900, Fujii Masao wrote: >> +# - Default Behavior - >> + >> +#vacuum_truncate = on # enable truncation after vacuum >> >> Since there's no existing GUC category that fits to vacuum_truncate, >> I'm fine with adding a new category like "Vacuuming" and placing >> vacuum_truncate there. >> >> However, if we do this, ISTM that the new category should also be added to >> guc_tables.h, and vacuum_truncate should be assigned to it in guc_tables.c. >> Additionally, the documentation should be updated to include >> the new category, with vacuum_truncate placed under it. Thought? > > Ah, you're right, I need to fix the category. Will post an updated patch > soon.
Here's a new version of the patch with the GUC placed in a new "Default Behavior" category for vacuum-related parameters. -- nathan
>From 28508114e193a3c9be6aca697c390b9bf790d0c8 Mon Sep 17 00:00:00 2001 From: Nathan Bossart <nat...@postgresql.org> Date: Tue, 18 Mar 2025 20:23:50 -0500 Subject: [PATCH v6 1/1] Add vacuum_truncate configuration parameter. This new parameter works just like the eponymous storage parameter: if set to true (which is the default), autovacuum and VACUUM attempt to truncate any empty pages at the end of the table. It is primarily intended to help users avoid locking issues on hot standbys. The setting can be overridden with the storage parameter or VACUUM's TRUNCATE option. Since there's presently no way to determine whether a Boolean storage parameter is explicitly set or has just picked up the default value, this commit also introduces an isset_offset member to relopt_parse_elt. Suggested-by: Will Storey <w...@summercat.com> Author: Nathan Bossart <nathandboss...@gmail.com> Co-authored-by: Gurjeet Singh <gurj...@singh.im> Reviewed-by: Laurenz Albe <laurenz.a...@cybertec.at> Reviewed-by: Fujii Masao <masao.fu...@oss.nttdata.com> Reviewed-by: Robert Treat <r...@xzilla.net> Discussion: https://postgr.es/m/Z2DE4lDX4tHqNGZt%40dev.null --- doc/src/sgml/config.sgml | 29 +++++++++++++++++++ doc/src/sgml/ref/create_table.sgml | 13 +++------ doc/src/sgml/ref/vacuum.sgml | 3 +- src/backend/access/common/reloptions.c | 14 ++++++++- src/backend/commands/vacuum.c | 17 ++++++++--- src/backend/utils/misc/guc_tables.c | 10 +++++++ src/backend/utils/misc/postgresql.conf.sample | 4 +++ src/include/access/reloptions.h | 1 + src/include/commands/vacuum.h | 1 + src/include/utils/guc_tables.h | 1 + src/include/utils/rel.h | 1 + src/test/regress/expected/vacuum.out | 27 +++++++++++++++++ src/test/regress/sql/vacuum.sql | 10 +++++++ 13 files changed, 116 insertions(+), 15 deletions(-) diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index 873290daa61..bdcefa8140b 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -9311,6 +9311,35 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv; </note> </sect2> + <sect2 id="runtime-config-vacuum-default"> + <title>Default Behavior</title> + + <variablelist> + <varlistentry id="guc-vacuum-truncate" xreflabel="vacuum_truncate"> + <term><varname>vacuum_truncate</varname> (<type>boolean</type>) + <indexterm> + <primary><varname>vacuum_truncate</varname> configuration parameter</primary> + </indexterm> + </term> + <listitem> + <para> + Enables or disables vacuum to try to truncate off any empty pages at + the end of the table. The default value is <literal>true</literal>. + If <literal>true</literal>, <command>VACUUM</command> and autovacuum + do the truncation and the disk space for the truncated pages is + returned to the operating system. Note that the truncation requires + an <literal>ACCESS EXCLUSIVE</literal> lock on the table. The + <literal>TRUNCATE</literal> parameter of + <link linkend="sql-vacuum"><command>VACUUM</command></link>, if + specified, overrides the value of this parameter. The setting can + also be overridden for individual tables by changing table storage + parameters. + </para> + </listitem> + </varlistentry> + </variablelist> + </sect2> + <sect2 id="runtime-config-vacuum-freezing"> <title>Freezing</title> diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml index 5304b738322..e5c034d724e 100644 --- a/doc/src/sgml/ref/create_table.sgml +++ b/doc/src/sgml/ref/create_table.sgml @@ -1692,15 +1692,10 @@ WITH ( MODULUS <replaceable class="parameter">numeric_literal</replaceable>, REM </term> <listitem> <para> - Enables or disables vacuum to try to truncate off any empty pages - at the end of this table. The default value is <literal>true</literal>. - If <literal>true</literal>, <command>VACUUM</command> and - autovacuum do the truncation and the disk space for - the truncated pages is returned to the operating system. - Note that the truncation requires <literal>ACCESS EXCLUSIVE</literal> - lock on the table. The <literal>TRUNCATE</literal> parameter - of <link linkend="sql-vacuum"><command>VACUUM</command></link>, if specified, overrides the value - of this option. + Per-table value for <xref linkend="guc-vacuum-truncate"/> parameter. The + <literal>TRUNCATE</literal> parameter of + <link linkend="sql-vacuum"><command>VACUUM</command></link>, if + specified, overrides the value of this option. </para> </listitem> </varlistentry> diff --git a/doc/src/sgml/ref/vacuum.sgml b/doc/src/sgml/ref/vacuum.sgml index 971b1237d47..bd5dcaf86a5 100644 --- a/doc/src/sgml/ref/vacuum.sgml +++ b/doc/src/sgml/ref/vacuum.sgml @@ -265,7 +265,8 @@ VACUUM [ ( <replaceable class="parameter">option</replaceable> [, ...] ) ] [ <re truncate off any empty pages at the end of the table and allow the disk space for the truncated pages to be returned to the operating system. This is normally the desired behavior - and is the default unless the <literal>vacuum_truncate</literal> + and is the default unless <xref linkend="guc-vacuum-truncate"/> + is set to false or the <literal>vacuum_truncate</literal> option has been set to false for the table to be vacuumed. Setting this option to false may be useful to avoid <literal>ACCESS EXCLUSIVE</literal> lock on the table that diff --git a/src/backend/access/common/reloptions.c b/src/backend/access/common/reloptions.c index 59fb53e7707..645b5c00467 100644 --- a/src/backend/access/common/reloptions.c +++ b/src/backend/access/common/reloptions.c @@ -1779,6 +1779,17 @@ fillRelOptions(void *rdopts, Size basesize, char *itempos = ((char *) rdopts) + elems[j].offset; char *string_val; + /* + * If isset_offset is provided, store whether the reloption is + * set there. + */ + if (elems[j].isset_offset > 0) + { + char *setpos = ((char *) rdopts) + elems[j].isset_offset; + + *(bool *) setpos = options[i].isset; + } + switch (options[i].gen->type) { case RELOPT_TYPE_BOOL: @@ -1901,7 +1912,7 @@ default_reloptions(Datum reloptions, bool validate, relopt_kind kind) {"vacuum_index_cleanup", RELOPT_TYPE_ENUM, offsetof(StdRdOptions, vacuum_index_cleanup)}, {"vacuum_truncate", RELOPT_TYPE_BOOL, - offsetof(StdRdOptions, vacuum_truncate)}, + offsetof(StdRdOptions, vacuum_truncate), offsetof(StdRdOptions, vacuum_truncate_set)}, {"vacuum_max_eager_freeze_failure_rate", RELOPT_TYPE_REAL, offsetof(StdRdOptions, vacuum_max_eager_freeze_failure_rate)} }; @@ -1981,6 +1992,7 @@ build_local_reloptions(local_relopts *relopts, Datum options, bool validate) elems[i].optname = opt->option->name; elems[i].opttype = opt->option->type; elems[i].offset = opt->offset; + elems[i].isset_offset = 0; /* not supported for local relopts yet */ i++; } diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c index e81c9a8aba3..f0a7b87808d 100644 --- a/src/backend/commands/vacuum.c +++ b/src/backend/commands/vacuum.c @@ -78,6 +78,7 @@ int vacuum_failsafe_age; int vacuum_multixact_failsafe_age; double vacuum_max_eager_freeze_failure_rate; bool track_cost_delay_timing; +bool vacuum_truncate; /* * Variables for cost-based vacuum delay. The defaults differ between @@ -2198,13 +2199,21 @@ vacuum_rel(Oid relid, RangeVar *relation, VacuumParams *params, ((StdRdOptions *) rel->rd_options)->vacuum_max_eager_freeze_failure_rate; /* - * Set truncate option based on truncate reloption if it wasn't specified - * in VACUUM command, or when running in an autovacuum worker + * Set truncate option based on truncate reloption or GUC if it wasn't + * specified in VACUUM command, or when running in an autovacuum worker */ if (params->truncate == VACOPTVALUE_UNSPECIFIED) { - if (rel->rd_options == NULL || - ((StdRdOptions *) rel->rd_options)->vacuum_truncate) + StdRdOptions *opts = (StdRdOptions *) rel->rd_options; + + if (opts && opts->vacuum_truncate_set) + { + if (opts->vacuum_truncate) + params->truncate = VACOPTVALUE_ENABLED; + else + params->truncate = VACOPTVALUE_DISABLED; + } + else if (vacuum_truncate) params->truncate = VACOPTVALUE_ENABLED; else params->truncate = VACOPTVALUE_DISABLED; diff --git a/src/backend/utils/misc/guc_tables.c b/src/backend/utils/misc/guc_tables.c index cc8f2b1230a..97cfd6e5a82 100644 --- a/src/backend/utils/misc/guc_tables.c +++ b/src/backend/utils/misc/guc_tables.c @@ -712,6 +712,7 @@ const char *const config_group_names[] = [STATS_CUMULATIVE] = gettext_noop("Statistics / Cumulative Query and Index Statistics"), [VACUUM_AUTOVACUUM] = gettext_noop("Vacuuming / Automatic Vacuuming"), [VACUUM_COST_DELAY] = gettext_noop("Vacuuming / Cost-Based Vacuum Delay"), + [VACUUM_DEFAULT] = gettext_noop("Vacuuming / Default Behavior"), [VACUUM_FREEZING] = gettext_noop("Vacuuming / Freezing"), [CLIENT_CONN_STATEMENT] = gettext_noop("Client Connection Defaults / Statement Behavior"), [CLIENT_CONN_LOCALE] = gettext_noop("Client Connection Defaults / Locale and Formatting"), @@ -2131,6 +2132,15 @@ struct config_bool ConfigureNamesBool[] = NULL, NULL, NULL }, + { + {"vacuum_truncate", PGC_USERSET, VACUUM_DEFAULT, + gettext_noop("Enables vacuum to truncate empty pages at the end of the table."), + }, + &vacuum_truncate, + true, + NULL, NULL, NULL + }, + /* End-of-list marker */ { {NULL, 0, 0, NULL, NULL}, NULL, false, NULL, NULL, NULL diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index ad54585cf1d..9f31e4071c7 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -714,6 +714,10 @@ autovacuum_worker_slots = 16 # autovacuum worker slots to allocate #vacuum_cost_page_dirty = 20 # 0-10000 credits #vacuum_cost_limit = 200 # 1-10000 credits +# - Default Behavior - + +#vacuum_truncate = on # enable truncation after vacuum + # - Freezing - #vacuum_freeze_table_age = 150000000 diff --git a/src/include/access/reloptions.h b/src/include/access/reloptions.h index 43445cdcc6c..146aed47c2d 100644 --- a/src/include/access/reloptions.h +++ b/src/include/access/reloptions.h @@ -152,6 +152,7 @@ typedef struct const char *optname; /* option's name */ relopt_type opttype; /* option's datatype */ int offset; /* offset of field in result struct */ + int isset_offset; /* if > 0, offset of "is set" field */ } relopt_parse_elt; /* Local reloption definition */ diff --git a/src/include/commands/vacuum.h b/src/include/commands/vacuum.h index baacc63f590..bc37a80dc74 100644 --- a/src/include/commands/vacuum.h +++ b/src/include/commands/vacuum.h @@ -304,6 +304,7 @@ extern PGDLLIMPORT int vacuum_multixact_freeze_table_age; extern PGDLLIMPORT int vacuum_failsafe_age; extern PGDLLIMPORT int vacuum_multixact_failsafe_age; extern PGDLLIMPORT bool track_cost_delay_timing; +extern PGDLLIMPORT bool vacuum_truncate; /* * Relevant for vacuums implementing eager scanning. Normal vacuums may diff --git a/src/include/utils/guc_tables.h b/src/include/utils/guc_tables.h index ab47145ec36..f72ce944d7f 100644 --- a/src/include/utils/guc_tables.h +++ b/src/include/utils/guc_tables.h @@ -89,6 +89,7 @@ enum config_group STATS_CUMULATIVE, VACUUM_AUTOVACUUM, VACUUM_COST_DELAY, + VACUUM_DEFAULT, VACUUM_FREEZING, CLIENT_CONN_STATEMENT, CLIENT_CONN_LOCALE, diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h index db3e504c3d2..d94fddd7cef 100644 --- a/src/include/utils/rel.h +++ b/src/include/utils/rel.h @@ -344,6 +344,7 @@ typedef struct StdRdOptions int parallel_workers; /* max number of parallel workers */ StdRdOptIndexCleanup vacuum_index_cleanup; /* controls index vacuuming */ bool vacuum_truncate; /* enables vacuum to truncate a relation */ + bool vacuum_truncate_set; /* whether vacuum_truncate is set */ /* * Fraction of pages in a relation that vacuum can eagerly scan and fail diff --git a/src/test/regress/expected/vacuum.out b/src/test/regress/expected/vacuum.out index 3f91b69b324..0abcc99989e 100644 --- a/src/test/regress/expected/vacuum.out +++ b/src/test/regress/expected/vacuum.out @@ -236,6 +236,7 @@ SELECT pg_relation_size('vac_truncate_test') > 0; t (1 row) +SET vacuum_truncate = false; VACUUM (DISABLE_PAGE_SKIPPING) vac_truncate_test; SELECT pg_relation_size('vac_truncate_test') = 0; ?column? @@ -244,6 +245,32 @@ SELECT pg_relation_size('vac_truncate_test') = 0; (1 row) VACUUM (TRUNCATE FALSE, FULL TRUE) vac_truncate_test; +ALTER TABLE vac_truncate_test RESET (vacuum_truncate); +INSERT INTO vac_truncate_test VALUES (1, NULL), (NULL, NULL); +ERROR: null value in column "i" of relation "vac_truncate_test" violates not-null constraint +DETAIL: Failing row contains (null, null). +VACUUM (DISABLE_PAGE_SKIPPING) vac_truncate_test; +SELECT pg_relation_size('vac_truncate_test') > 0; + ?column? +---------- + t +(1 row) + +RESET vacuum_truncate; +VACUUM (TRUNCATE FALSE, DISABLE_PAGE_SKIPPING) vac_truncate_test; +SELECT pg_relation_size('vac_truncate_test') > 0; + ?column? +---------- + t +(1 row) + +VACUUM (DISABLE_PAGE_SKIPPING) vac_truncate_test; +SELECT pg_relation_size('vac_truncate_test') = 0; + ?column? +---------- + t +(1 row) + DROP TABLE vac_truncate_test; -- partitioned table CREATE TABLE vacparted (a int, b char) PARTITION BY LIST (a); diff --git a/src/test/regress/sql/vacuum.sql b/src/test/regress/sql/vacuum.sql index 058add027f1..a72bdb5b619 100644 --- a/src/test/regress/sql/vacuum.sql +++ b/src/test/regress/sql/vacuum.sql @@ -194,9 +194,19 @@ CREATE TEMP TABLE vac_truncate_test(i INT NOT NULL, j text) INSERT INTO vac_truncate_test VALUES (1, NULL), (NULL, NULL); VACUUM (TRUNCATE FALSE, DISABLE_PAGE_SKIPPING) vac_truncate_test; SELECT pg_relation_size('vac_truncate_test') > 0; +SET vacuum_truncate = false; VACUUM (DISABLE_PAGE_SKIPPING) vac_truncate_test; SELECT pg_relation_size('vac_truncate_test') = 0; VACUUM (TRUNCATE FALSE, FULL TRUE) vac_truncate_test; +ALTER TABLE vac_truncate_test RESET (vacuum_truncate); +INSERT INTO vac_truncate_test VALUES (1, NULL), (NULL, NULL); +VACUUM (DISABLE_PAGE_SKIPPING) vac_truncate_test; +SELECT pg_relation_size('vac_truncate_test') > 0; +RESET vacuum_truncate; +VACUUM (TRUNCATE FALSE, DISABLE_PAGE_SKIPPING) vac_truncate_test; +SELECT pg_relation_size('vac_truncate_test') > 0; +VACUUM (DISABLE_PAGE_SKIPPING) vac_truncate_test; +SELECT pg_relation_size('vac_truncate_test') = 0; DROP TABLE vac_truncate_test; -- partitioned table -- 2.39.5 (Apple Git-154)
