VACUUM(7)
π VACUUM π
okay so bestie, welcome to the PostgreSQL 13.23 manual page for VACUUM(7) β the literal glow-up your database needs when dead tuples are just sitting there being extra. β¨
β¨ NAME β¨
VACUUM β garbage-collect and optionally analyze a database. Thatβs the whole vibe: clean up dead stuff, and if you want, refresh the stats too. π§Ήπ
π¦ SYNOPSIS π¦
VACUUM [ ( option [, ...] ) ] [ table_and_columns [, ...] ]
VACUUM [ FULL ] [ FREEZE ] [ VERBOSE ] [ ANALYZE ] [ table_and_columns [, ...] ]
where option can be one of:
FULL [ boolean ]
FREEZE [ boolean ]
VERBOSE [ boolean ]
ANALYZE [ boolean ]
DISABLE_PAGE_SKIPPING [ boolean ]
SKIP_LOCKED [ boolean ]
INDEX_CLEANUP [ boolean ]
TRUNCATE [ boolean ]
PARALLEL integer
and table_and_columns is:
table_name [ ( column_name [, ...] ) ]
π DESCRIPTION π
VACUUM reclaims storage occupied by dead tuples. In normal PostgreSQL operation, tuples that are deleted or obsoleted by an update are not physically removed from their table; they remain present until a VACUUM is done. Therefore itβs necessary to do VACUUM periodically, especially on frequently-updated tables. π«Ά
Without a table_and_columns list, VACUUM processes every table and materialized view in the current database that the current user has permission to vacuum. With a list, VACUUM processes only those table(s). π
VACUUM ANALYZE performs a VACUUM and then an ANALYZE for each selected table. This is a handy combination form for routine maintenance scripts. See ANALYZE(7) for more details about its processing. πΈ
Plain VACUUM (without FULL) simply reclaims space and makes it available for re-use. This form of the command can operate in parallel with normal reading and writing of the table, as an exclusive lock is not obtained. However, extra space is not returned to the operating system (in most cases); itβs just kept available for re-use within the same table. It also allows us to leverage multiple CPUs in order to process indexes. This feature is known as parallel vacuum. To disable this feature, one can use PARALLEL option and specify parallel workers as zero. VACUUM FULL rewrites the entire contents of the table into a new disk file with no extra space, allowing unused space to be returned to the operating system. This form is much slower and requires an ACCESS EXCLUSIVE lock on each table while it is being processed. π₯
When the option list is surrounded by parentheses, the options can be written in any order. Without parentheses, options must be specified in exactly the order shown above. The parenthesized syntax was added in PostgreSQL 9.0; the unparenthesized syntax is deprecated. π¨
π¨ bestie, fr fr: the unparenthesized syntax is deprecated. Use the parentheses when you can, okay?
π PARAMETERS π
FULLβ Selects βfullβ vacuum, which can reclaim more space, but takes much longer and exclusively locks the table. This method also requires extra disk space, since it writes a new copy of the table and doesnβt release the old copy until the operation is complete. Usually this should only be used when a significant amount of space needs to be reclaimed from within the table. πFREEZEβ Selects aggressive βfreezingβ of tuples. SpecifyingFREEZEis equivalent to performingVACUUMwith thevacuum_freeze_min_ageandvacuum_freeze_table_ageparameters set to zero. Aggressive freezing is always performed when the table is rewritten, so this option is redundant whenFULLis specified. π§VERBOSEβ Prints a detailed vacuum activity report for each table. π£οΈANALYZEβ Updates statistics used by the planner to determine the most efficient way to execute a query. πDISABLE_PAGE_SKIPPINGβ Normally,VACUUMwill skip pages based on the visibility map. Pages where all tuples are known to be frozen can always be skipped, and those where all tuples are known to be visible to all transactions may be skipped except when performing an aggressive vacuum. Furthermore, except when performing an aggressive vacuum, some pages may be skipped in order to avoid waiting for other sessions to finish using them. This option disables all page-skipping behavior, and is intended to be used only when the contents of the visibility map are suspect, which should happen only if there is a hardware or software issue causing database corruption. π«£SKIP_LOCKEDβ Specifies thatVACUUMshould not wait for any conflicting locks to be released when beginning work on a relation: if a relation cannot be locked immediately without waiting, the relation is skipped. Note that even with this option,VACUUMmay still block when opening the relationβs indexes. Additionally,VACUUM ANALYZEmay still block when acquiring sample rows from partitions, table inheritance children, and some types of foreign tables. Also, whileVACUUMordinarily processes all partitions of specified partitioned tables, this option will causeVACUUMto skip all partitions if there is a conflicting lock on the partitioned table. πINDEX_CLEANUPβ Specifies thatVACUUMshould attempt to remove index entries pointing to dead tuples. This is normally the desired behavior and is the default unless thevacuum_index_cleanupoption has been set tofalsefor the table to be vacuumed. Setting this option tofalsemay be useful when it is necessary to make vacuum run as quickly as possible, for example to avoid imminent transaction ID wraparound (see Section 24.1.5). However, if index cleanup is not performed regularly, performance may suffer, because as the table is modified, indexes will accumulate dead tuples and the table itself will accumulate dead line pointers that cannot be removed until index cleanup is completed. This option has no effect for tables that do not have an index and is ignored if theFULLoption is used. π§ΉTRUNCATEβ Specifies thatVACUUMshould attempt to 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 thevacuum_truncateoption has been set tofalsefor the table to be vacuumed. Setting this option tofalsemay be useful to avoidACCESS EXCLUSIVElock on the table that the truncation requires. This option is ignored if theFULLoption is used. βοΈPARALLELβ Perform index vacuum and index cleanup phases ofVACUUMin parallel usingintegerbackground workers (for the details of each vacuum phase, please refer to Table 27.37). The number of workers used to perform the operation is equal to the number of indexes on the relation that support parallel vacuum which is limited by the number of workers specified withPARALLELoption if any which is further limited bymax_parallel_maintenance_workers. An index can participate in parallel vacuum if and only if the size of the index is more thanmin_parallel_index_scan_size. Please note that it is not guaranteed that the number of parallel workers specified inintegerwill 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 2 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 canβt be used with theFULLoption. π―booleanβ Specifies whether the selected option should be turned on or off. You can writeTRUE,ON, or1to enable the option, andFALSE,OFF, or0to disable it. The boolean value can also be omitted, in which caseTRUEis assumed. βintegerβ Specifies a non-negative integer value passed to the selected option. π’table_nameβ The name (optionally schema-qualified) of a specific table or materialized view to vacuum. If the specified table is a partitioned table, all of its leaf partitions are vacuumed. ποΈcolumn_nameβ The name of a specific column to analyze. Defaults to all columns. If a column list is specified,ANALYZEmust also be specified. π§
π₯ OUTPUTS π₯
When VERBOSE is specified, VACUUM emits progress messages to indicate which table is currently being processed. Various statistics about the tables are printed as well. π
β NOTES β
To vacuum a table, one must ordinarily be the tableβs owner or a superuser. However, database owners are allowed to vacuum all tables in their databases, except shared catalogs. (The restriction for shared catalogs means that a true database-wide VACUUM can only be performed by a superuser.) VACUUM will skip over any tables that the calling user does not have permission to vacuum. π
VACUUM cannot be executed inside a transaction block. π«
For tables with GIN indexes, VACUUM (in any form) also completes any pending index insertions, by moving pending index entries to the appropriate places in the main GIN index structure. See Section 66.4.1 for details. π
We recommend that active production databases be vacuumed frequently (at least nightly), in order to remove dead rows. After adding or deleting a large number of rows, it might be a good idea to issue a VACUUM ANALYZE command for the affected table. This will update the system catalogs with the results of all recent changes, and allow the PostgreSQL query planner to make better choices in planning queries. π
The FULL option is not recommended for routine use, but might be useful in special cases. An example is when you have deleted or updated most of the rows in a table and would like the table to physically shrink to occupy less disk space and allow faster table scans. VACUUM FULL will usually shrink the table more than a plain VACUUM would. π«Ά
The PARALLEL option is used only for vacuum purposes. If this option is specified with the ANALYZE option, it does not affect ANALYZE. π
VACUUM causes a substantial increase in I/O traffic, which might cause poor performance for other active sessions. Therefore, it is sometimes advisable to use the cost-based vacuum delay feature. For parallel vacuum, each worker sleeps in proportion to the work done by that worker. See Section 19.4.4 for details. π΄
PostgreSQL includes an βautovacuumβ facility which can automate routine vacuum maintenance. For more information about automatic and manual vacuuming, see Section 24.1. π€
π EXAMPLES π
To clean a single table onek, analyze it for the optimizer and print a detailed vacuum activity report:
VACUUM (VERBOSE, ANALYZE) onek;
π COMPATIBILITY π
There is no VACUUM statement in the SQL standard. periodt. π
π«Ά SEE ALSO π«Ά
vacuumdb(1), Section 19.4.4, Section 24.1.6
mwah π β thatβs the PostgreSQL 13.23, 2025, VACUUM(7) manual page, bestie. now go let your database breathe β¨
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