From d5c35ceb53461adf0b7bacc71c016c8e150523ae Mon Sep 17 00:00:00 2001 From: Nathan Bossart Date: Tue, 18 Mar 2025 20:23:50 -0500 Subject: [PATCH] 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 Author: Nathan Bossart Co-authored-by: Gurjeet Singh Reviewed-by: Laurenz Albe Reviewed-by: Fujii Masao Reviewed-by: Robert Treat 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 873290daa613..bdcefa8140b4 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; + + Default Behavior + + + + vacuum_truncate (boolean) + + vacuum_truncate configuration parameter + + + + + Enables or disables vacuum to try to truncate off any empty pages at + the end of the table. The default value is true. + If true, VACUUM 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 ACCESS EXCLUSIVE lock on the table. The + TRUNCATE parameter of + VACUUM, if + specified, overrides the value of this parameter. The setting can + also be overridden for individual tables by changing table storage + parameters. + + + + + + Freezing diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgml index 5304b7383225..e5c034d724e4 100644 --- a/doc/src/sgml/ref/create_table.sgml +++ b/doc/src/sgml/ref/create_table.sgml @@ -1692,15 +1692,10 @@ WITH ( MODULUS numeric_literal, REM - Enables or disables vacuum to try to truncate off any empty pages - at the end of this table. The default value is true. - If true, VACUUM and - autovacuum do the truncation and the disk space for - the truncated pages is returned to the operating system. - Note that the truncation requires ACCESS EXCLUSIVE - lock on the table. The TRUNCATE parameter - of VACUUM, if specified, overrides the value - of this option. + Per-table value for parameter. The + TRUNCATE parameter of + VACUUM, if + specified, overrides the value of this option. diff --git a/doc/src/sgml/ref/vacuum.sgml b/doc/src/sgml/ref/vacuum.sgml index 971b1237d47e..bd5dcaf86a5c 100644 --- a/doc/src/sgml/ref/vacuum.sgml +++ b/doc/src/sgml/ref/vacuum.sgml @@ -265,7 +265,8 @@ VACUUM [ ( option [, ...] ) ] [ vacuum_truncate + and is the default unless + is set to false or the vacuum_truncate option has been set to false for the table to be vacuumed. Setting this option to false may be useful to avoid ACCESS EXCLUSIVE lock on the table that diff --git a/src/backend/access/common/reloptions.c b/src/backend/access/common/reloptions.c index 59fb53e77071..645b5c00467d 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 e81c9a8aba3e..f0a7b87808d1 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 cc8f2b1230a2..97cfd6e5a822 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 ad54585cf1d0..9f31e4071c7b 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 43445cdcc6c0..146aed47c2d6 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 baacc63f5909..bc37a80dc74f 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 ab47145ec36c..f72ce944d7f9 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 db3e504c3d2d..d94fddd7cef7 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 3f91b69b3248..0abcc99989e0 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 058add027f13..a72bdb5b619d 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