ANALYZE(7)

✨ ANALYZE(7) ✨

okay bestie, you know how the query planner is out here making ✨decisions✨ about how to run your queries? Yeah. ANALYZE is the thing that feeds it the tea it needs. It's a PostgreSQL 18.6 joint. Let's go 💅

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🌸 NAME 🌸

ANALYZE — collect statistics about a database

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🎀 SYNOPSIS 🎀

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

and option can be literally any one of these:

    VERBOSE [ boolean ]
    SKIP_LOCKED [ boolean ]
    BUFFER_USAGE_LIMIT size

and table_and_columns is giving:

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

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💖 DESCRIPTION 💖

So like. ANALYZE goes and collects statistics about what's actually inside the tables in your database, and then it stores all of that in the pg_statistic system catalog. After that, the query planner uses those stats to figure out the most efficient execution plans for your queries. It's basically the planner's gossip source. No stats, no good plans, iykyk 😭

If you don't give it a table_and_columns list, ANALYZE processes every table and materialized view in the current database that the current user has permission to analyze. Give it a list and it only touches those table(s). You can go even further and hand it a list of column names for a table, in which case only the statistics for those columns get collected. selective queen ✨

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🦋 PARAMETERS 🦋

• VERBOSE — turns on display of progress messages at INFO level. So you can watch it work. main character behavior fr.
• SKIP_LOCKED — says that ANALYZE should not wait around for conflicting locks to be released when it's beginning work on a relation: if a relation can't be locked immediately without waiting, it just gets skipped. 💀 Heads up though: 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's a conflicting lock on the partitioned table.
• BUFFER_USAGE_LIMIT — specifies the Buffer Access Strategy ring buffer size for ANALYZE. This size is used to calculate the number of shared buffers which will be reused as part of this strategy. 0 disables use of a Buffer Access Strategy. When this option isn't specified, ANALYZE uses the value from vacuum_buffer_usage_limit. Higher settings can let ANALYZE run more quickly, but a setting that's too large may cause too many other useful pages to be evicted from shared buffers. The minimum value is 128 kB and the maximum value is 16 GB.
• 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. (default behavior, love that for us 🫶)
• size — specifies an amount of memory in kilobytes. Sizes may also be specified as a string containing the numerical size followed by any one of the following memory units: B (bytes), kB (kilobytes), MB (megabytes), GB (gigabytes), or TB (terabytes).
• 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 ONLY is specified before the table name, only that table is analyzed. If ONLY is not specified, the table and all its inheritance child tables or partitions (if any) are analyzed. Optionally, * can be specified after the table name to explicitly indicate that inheritance child tables (or partitions) are to be analyzed.
• column_name — the name of a specific column to analyze. Defaults to all columns.

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🌈 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. it's giving live commentary 🎀

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👑 NOTES 👑

To analyze a table, one must ordinarily have the MAINTAIN privilege on the table. However, database owners are allowed to analyze all tables in their databases, except shared catalogs. ANALYZE will skip over any tables that the calling user does not have permission to analyze. (respectfully, it just moves on 💅)

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 24.1.6) 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's 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.) 🕐

While ANALYZE is running, the search_path is temporarily changed to pg_catalog, pg_temp.

ANALYZE requires only a read lock on the target table, so it can run in parallel with other non-DDL activity on the table. slay, no blocking ✨

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's more information about the statistics in Chapter 24.

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. (yes bestie, it's a little chaotic, it's fine 🫠)

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. bye bestie, not needed 👋

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 = ...). manual override, we love a hands-on moment 💅

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 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. By default, ANALYZE will also recursively collect and update the statistics for each inheritance child table. The ONLY keyword may be used to disable this.

For partitioned tables, ANALYZE gathers statistics by sampling rows from all partitions. By default, ANALYZE will also recursively collect and update the statistics for each partition. The ONLY keyword may be used to disable this.

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. 😤 do it yourself era

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 27.4.1 for details. 👀

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💀 COMPATIBILITY 💀

There is no ANALYZE statement in the SQL standard. it's a postgres original, no cap 💅

The following syntax was used before PostgreSQL version 11 and is still supported:

    ANALYZE [ VERBOSE ] [ table_and_columns [, ...] ]

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🔥 SEE ALSO 🔥

VACUUM(7), vacuumdb(1), Section 19.10.2, Section 24.1.6, Section 27.4.1

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okay that's the whole page bestie, go forth and gather some stats 🦋✨

This was PostgreSQL 18.6 documentation, dated 2026 — ANALYZE(7). mwah 💖