From: Nathan Bossart <nathan@postgresql.org>
Subject: [PATCH v2 1/1] Add vacuum_truncate GUC.
Date: Thu, 27 Feb 2025 21:09:37 -0600
---
doc/src/sgml/config.sgml | 22 +++++++++++++++++++
doc/src/sgml/ref/create_table.sgml | 10 +--------
doc/src/sgml/ref/vacuum.sgml | 3 ++-
src/backend/access/common/reloptions.c | 11 ++++++++--
src/backend/commands/vacuum.c | 17 ++++++++++----
src/backend/utils/misc/guc_tables.c | 9 ++++++++
src/backend/utils/misc/postgresql.conf.sample | 1 +
src/include/access/reloptions.h | 1 +
src/include/commands/vacuum.h | 1 +
src/include/utils/rel.h | 1 +
10 files changed, 60 insertions(+), 16 deletions(-)
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgmlindex e55700f35b8..069ac35762f 100644--- a/doc/src/sgml/config.sgml+++ b/doc/src/sgml/config.sgml@@ -8934,6 +8934,28 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv;
</listitem>
</varlistentry>
+ <varlistentry id="guc-vacuum-truncate" xreflabel="autovacuum">+ <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 be+ overridden for individual tables by changing table storage parameters.+ </para>+ </listitem>+ </varlistentry>+
</variablelist>
</sect2>
diff --git a/doc/src/sgml/ref/create_table.sgml b/doc/src/sgml/ref/create_table.sgmlindex 0a3e520f215..3c2315b1a8e 100644--- a/doc/src/sgml/ref/create_table.sgml+++ b/doc/src/sgml/ref/create_table.sgml@@ -1688,15 +1688,7 @@ 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.
</para>
</listitem>
</varlistentry>
diff --git a/doc/src/sgml/ref/vacuum.sgml b/doc/src/sgml/ref/vacuum.sgmlindex 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.cindex 59fb53e7707..c0a7c0832ab 100644--- a/src/backend/access/common/reloptions.c+++ b/src/backend/access/common/reloptions.c@@ -1779,6 +1779,13 @@ fillRelOptions(void *rdopts, Size basesize,
char *itempos = ((char *) rdopts) + elems[j].offset;
char *string_val;
+ 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 +1908,7 @@ 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)}
};
@@ -1968,7 +1975,7 @@ void *
build_local_reloptions(local_relopts *relopts, Datum options, bool validate)
{
int noptions = list_length(relopts->options);
- relopt_parse_elt *elems = palloc(sizeof(*elems) * noptions);+ relopt_parse_elt *elems = palloc0(sizeof(*elems) * noptions);
relopt_value *vals;
void *opts;
int i = 0;
diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.cindex 0239d9bae65..b12c623be0a 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
@@ -2192,13 +2193,21 @@ 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.cindex ad25cbb39c5..e38fe56d3c2 100644--- a/src/backend/utils/misc/guc_tables.c+++ b/src/backend/utils/misc/guc_tables.c@@ -2118,6 +2118,15 @@ struct config_bool ConfigureNamesBool[] =
NULL, NULL, NULL
},
+ {+ {"vacuum_truncate", PGC_USERSET, VACUUM_AUTOVACUUM,+ 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.sampleindex 5362ff80519..de012617898 100644--- a/src/backend/utils/misc/postgresql.conf.sample+++ b/src/backend/utils/misc/postgresql.conf.sample@@ -692,6 +692,7 @@ autovacuum_worker_slots = 16 # autovacuum worker slots to allocate
#autovacuum_vacuum_cost_limit = -1 # default vacuum cost limit for
# autovacuum, -1 means use
# vacuum_cost_limit
+#vacuum_truncate = on # enable truncation after vacuum
# - Cost-Based Vacuum Delay -
diff --git a/src/include/access/reloptions.h b/src/include/access/reloptions.hindex 43445cdcc6c..61e58a5daa3 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 "set" field */
} relopt_parse_elt;
/* Local reloption definition */
diff --git a/src/include/commands/vacuum.h b/src/include/commands/vacuum.hindex 1571a66c6bf..d6770e2d44a 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/rel.h b/src/include/utils/rel.hindex 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
--
2.39.5 (Apple Git-154)
--WPB+5+kPQlKEwC0K--
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To: pgsql-general@postgresql.org
Cc: nathan@postgresql.org
Subject: Re: [PATCH v2 1/1] Add vacuum_truncate GUC.
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