1VACUUM(7) PostgreSQL 10.7 Documentation VACUUM(7)
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6 VACUUM - garbage-collect and optionally analyze a database
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9 VACUUM [ ( { FULL | FREEZE | VERBOSE | ANALYZE | DISABLE_PAGE_SKIPPING } [, ...] ) ] [ table_name [ (column_name [, ...] ) ] ]
10 VACUUM [ FULL ] [ FREEZE ] [ VERBOSE ] [ table_name ]
11 VACUUM [ FULL ] [ FREEZE ] [ VERBOSE ] ANALYZE [ table_name [ (column_name [, ...] ) ] ]
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14 VACUUM reclaims storage occupied by dead tuples. In normal PostgreSQL
15 operation, tuples that are deleted or obsoleted by an update are not
16 physically removed from their table; they remain present until a VACUUM
17 is done. Therefore it's necessary to do VACUUM periodically, especially
18 on frequently-updated tables.
19 With no parameter, VACUUM processes every table in the current database
21 that the current user has permission to vacuum. With a parameter,
22 VACUUM processes only that table.
23 VACUUM ANALYZE performs a VACUUM and then an ANALYZE for each selected
25 table. This is a handy combination form for routine maintenance
26 scripts. See ANALYZE(7) for more details about its processing.
27 Plain VACUUM (without FULL) simply reclaims space and makes it
29 available for re-use. This form of the command can operate in parallel
30 with normal reading and writing of the table, as an exclusive lock is
31 not obtained. However, extra space is not returned to the operating
32 system (in most cases); it's just kept available for re-use within the
33 same table. VACUUM FULL rewrites the entire contents of the table into
34 a new disk file with no extra space, allowing unused space to be
35 returned to the operating system. This form is much slower and requires
36 an exclusive lock on each table while it is being processed.
37 When the option list is surrounded by parentheses, the options can be
39 written in any order. Without parentheses, options must be specified in
40 exactly the order shown above. The parenthesized syntax was added in
41 PostgreSQL 9.0; the unparenthesized syntax is deprecated.
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44 FULL
45 Selects “full” vacuum, which can reclaim more space, but takes much
46 longer and exclusively locks the table. This method also requires
47 extra disk space, since it writes a new copy of the table and
48 doesn't release the old copy until the operation is complete.
49 Usually this should only be used when a significant amount of space
50 needs to be reclaimed from within the table.
51 FREEZE
53 Selects aggressive “freezing” of tuples. Specifying FREEZE is
54 equivalent to performing VACUUM with the vacuum_freeze_min_age and
55 vacuum_freeze_table_age parameters set to zero. Aggressive freezing
56 is always performed when the table is rewritten, so this option is
57 redundant when FULL is specified.
58 VERBOSE
60 Prints a detailed vacuum activity report for each table.
61 ANALYZE
63 Updates statistics used by the planner to determine the most
64 efficient way to execute a query.
65 DISABLE_PAGE_SKIPPING
67 Normally, VACUUM will skip pages based on the visibility map. Pages
68 where all tuples are known to be frozen can always be skipped, and
69 those where all tuples are known to be visible to all transactions
70 may be skipped except when performing an aggressive vacuum.
71 Furthermore, except when performing an aggressive vacuum, some
72 pages may be skipped in order to avoid waiting for other sessions
73 to finish using them. This option disables all page-skipping
74 behavior, and is intended to be used only the contents of the
75 visibility map are thought to be suspect, which should happen only
76 if there is a hardware or software issue causing database
77 corruption.
78 table_name
80 The name (optionally schema-qualified) of a specific table to
81 vacuum. If omitted, all regular tables and materialized views in
82 the current database are vacuumed. If the specified table is a
83 partitioned table, all of its leaf partitions are vacuumed.
84 column_name
86 The name of a specific column to analyze. Defaults to all columns.
87 If a column list is specified, ANALYZE is implied.
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90 When VERBOSE is specified, VACUUM emits progress messages to indicate
91 which table is currently being processed. Various statistics about the
92 tables are printed as well.
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95 To vacuum a table, one must ordinarily be the table's owner or a
96 superuser. However, database owners are allowed to vacuum all tables in
97 their databases, except shared catalogs. (The restriction for shared
98 catalogs means that a true database-wide VACUUM can only be performed
99 by a superuser.) VACUUM will skip over any tables that the calling
100 user does not have permission to vacuum.
101 VACUUM cannot be executed inside a transaction block.
103 For tables with GIN indexes, VACUUM (in any form) also completes any
105 pending index insertions, by moving pending index entries to the
106 appropriate places in the main GIN index structure. See Section 64.4.1
107 for details.
108 We recommend that active production databases be vacuumed frequently
110 (at least nightly), in order to remove dead rows. After adding or
111 deleting a large number of rows, it might be a good idea to issue a
112 VACUUM ANALYZE command for the affected table. This will update the
113 system catalogs with the results of all recent changes, and allow the
114 PostgreSQL query planner to make better choices in planning queries.
115 The FULL option is not recommended for routine use, but might be useful
117 in special cases. An example is when you have deleted or updated most
118 of the rows in a table and would like the table to physically shrink to
119 occupy less disk space and allow faster table scans. VACUUM FULL will
120 usually shrink the table more than a plain VACUUM would.
121 VACUUM causes a substantial increase in I/O traffic, which might cause
123 poor performance for other active sessions. Therefore, it is sometimes
124 advisable to use the cost-based vacuum delay feature. See
125 Section 19.4.4 for details.
126 PostgreSQL includes an “autovacuum” facility which can automate routine
128 vacuum maintenance. For more information about automatic and manual
129 vacuuming, see Section 24.1.
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132 To clean a single table onek, analyze it for the optimizer and print a
133 detailed vacuum activity report:
134 VACUUM (VERBOSE, ANALYZE) onek;
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138 There is no VACUUM statement in the SQL standard.
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141 vacuumdb(1), Section 19.4.4, Section 24.1.6
142PostgreSQL 10.7 2019 VACUUM(7)