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ANALYZE(7)                         PostgreSQL 14.23 Documentation                         ANALYZE(7)



NAME
       ANALYZE - collect statistics about a database

SYNOPSIS
       ANALYZE [ ( option [, ...] ) ] [ table_and_columns [, ...] ]
       ANALYZE [ VERBOSE ] [ table_and_columns [, ...] ]

       where option can be one of:

           VERBOSE [ boolean ]
           SKIP_LOCKED [ boolean ]

       and table_and_columns is:

           table_name [ ( column_name [, ...] ) ]

DESCRIPTION
       ANALYZE collects statistics about the contents of tables in the database, and stores the
       results in the pg_statistic system catalog. Subsequently, the query planner uses these
       statistics to help determine the most efficient execution plans for queries.

       Without a table_and_columns list, ANALYZE processes every table and materialized view in the
       current database that the current user has permission to analyze. With a list, ANALYZE
       processes only those table(s). It is further possible to give a list of column names for a
       table, in which case only the statistics for those columns are collected.

       When the option list is surrounded by parentheses, the options can be written in any order.
       The parenthesized syntax was added in PostgreSQL 11; the unparenthesized syntax is
       deprecated.

PARAMETERS
       VERBOSE
           Enables display of progress messages.

       SKIP_LOCKED
           Specifies that ANALYZE should 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, ANALYZE may still block when
           opening the relation's indexes or when acquiring sample rows from partitions, table
           inheritance children, and some types of foreign tables. Also, while ANALYZE ordinarily
           processes all partitions of specified partitioned tables, this option will cause ANALYZE
           to skip all partitions if there is a conflicting lock on the partitioned table.

       boolean
           Specifies whether the selected option should be turned on or off. You can write TRUE, ON,
           or 1 to enable the option, and FALSE, OFF, or 0 to disable it. The boolean value can also
           be omitted, in which case TRUE is assumed.

       table_name
           The name (possibly schema-qualified) of a specific table to analyze. If omitted, all
           regular tables, partitioned tables, and materialized views in the current database are
           analyzed (but not foreign tables). If the specified table is a partitioned table, both
           the inheritance statistics of the partitioned table as a whole and statistics of the
           individual partitions are updated.

       column_name
           The name of a specific column to analyze. Defaults to all columns.

OUTPUTS
       When VERBOSE is specified, ANALYZE emits progress messages to indicate which table is
       currently being processed. Various statistics about the tables are printed as well.

NOTES
       To analyze a table, one must ordinarily be the table's owner or a superuser. However,
       database owners are allowed to analyze all tables in their databases, except shared catalogs.
       (The restriction for shared catalogs means that a true database-wide ANALYZE can only be
       performed by a superuser.)  ANALYZE will skip over any tables that the calling user does not
       have permission to analyze.

       Foreign tables are analyzed only when explicitly selected. Not all foreign data wrappers
       support ANALYZE. If the table's wrapper does not support ANALYZE, the command prints a
       warning and does nothing.

       In the default PostgreSQL configuration, the autovacuum daemon (see Section 25.1.6) takes
       care of automatic analyzing of tables when they are first loaded with data, and as they
       change throughout regular operation. When autovacuum is disabled, it is a good idea to run
       ANALYZE periodically, or just after making major changes in the contents of a table. Accurate
       statistics will help the planner to choose the most appropriate query plan, and thereby
       improve the speed of query processing. A common strategy for read-mostly databases is to run
       VACUUM and ANALYZE once a day during a low-usage time of day. (This will not be sufficient if
       there is heavy update activity.)

       ANALYZE requires only a read lock on the target table, so it can run in parallel with other
       activity on the table.

       The statistics collected by ANALYZE usually include a list of some of the most common values
       in each column and a histogram showing the approximate data distribution in each column. One
       or both of these can be omitted if ANALYZE deems them uninteresting (for example, in a
       unique-key column, there are no common values) or if the column data type does not support
       the appropriate operators. There is more information about the statistics in Chapter 25.

       For large tables, ANALYZE takes a random sample of the table contents, rather than examining
       every row. This allows even very large tables to be analyzed in a small amount of time. Note,
       however, that the statistics are only approximate, and will change slightly each time ANALYZE
       is run, even if the actual table contents did not change. This might result in small changes
       in the planner's estimated costs shown by EXPLAIN. In rare situations, this non-determinism
       will cause the planner's choices of query plans to change after ANALYZE is run. To avoid
       this, raise the amount of statistics collected by ANALYZE, as described below.

       The extent of analysis can be controlled by adjusting the default_statistics_target
       configuration variable, or on a column-by-column basis by setting the per-column statistics
       target with ALTER TABLE ... ALTER COLUMN ... SET STATISTICS. The target value sets the
       maximum number of entries in the most-common-value list and the maximum number of bins in the
       histogram. The default target value is 100, but this can be adjusted up or down to trade off
       accuracy of planner estimates against the time taken for ANALYZE and the amount of space
       occupied in pg_statistic. In particular, setting the statistics target to zero disables
       collection of statistics for that column. It might be useful to do that for columns that are
       never used as part of the WHERE, GROUP BY, or ORDER BY clauses of queries, since the planner
       will have no use for statistics on such columns.

       The largest statistics target among the columns being analyzed determines the number of table
       rows sampled to prepare the statistics. Increasing the target causes a proportional increase
       in the time and space needed to do ANALYZE.

       One of the values estimated by ANALYZE is the number of distinct values that appear in each
       column. Because only a subset of the rows are examined, this estimate can sometimes be quite
       inaccurate, even with the largest possible statistics target. If this inaccuracy leads to bad
       query plans, a more accurate value can be determined manually and then installed with ALTER
       TABLE ... ALTER COLUMN ... SET (n_distinct = ...).

       If the table being analyzed has inheritance children, ANALYZE gathers two sets of statistics:
       one on the rows of the parent table only, and a second including rows of both the parent
       table and all of its children. This second set of statistics is needed when planning queries
       that process the inheritance tree as a whole. The child tables themselves are not
       individually analyzed in this case. The autovacuum daemon, however, will only consider
       inserts or updates on the parent table itself when deciding whether to trigger an automatic
       analyze for that table. If that table is rarely inserted into or updated, the inheritance
       statistics will not be up to date unless you run ANALYZE manually.

       For partitioned tables, ANALYZE gathers statistics by sampling rows from all partitions; in
       addition, it will recurse into each partition and update its statistics. Each leaf partition
       is analyzed only once, even with multi-level partitioning. No statistics are collected for
       only the parent table (without data from its partitions), because with partitioning it's
       guaranteed to be empty.

       The autovacuum daemon does not process partitioned tables, nor does it process inheritance
       parents if only the children are ever modified. It is usually necessary to periodically run a
       manual ANALYZE to keep the statistics of the table hierarchy up to date.

       If any child tables or partitions are foreign tables whose foreign data wrappers do not
       support ANALYZE, those tables are ignored while gathering inheritance statistics.

       If the table being analyzed is completely empty, ANALYZE will not record new statistics for
       that table. Any existing statistics will be retained.

       Each backend running ANALYZE will report its progress in the pg_stat_progress_analyze view.
       See Section 28.4.1 for details.

COMPATIBILITY
       There is no ANALYZE statement in the SQL standard.

SEE ALSO
       VACUUM(7), vacuumdb(1), Section 20.4.4, Section 25.1.6, Section 28.4.1



PostgreSQL 14.23                                2026                                      ANALYZE(7)