pg_stat_statements: Query Performance Monitoring
pg_stat_statements is a database extension that exposes a view, of the same name, to track statistics about SQL statements executed on the database. The following table shows some of the available statistics and metadata:
|userid oid (references pg_authid.oid)||OID of user who executed the statement|
|dbid oid (references pg_database.oid)||OID of database in which the statement was executed|
|toplevel bool||True if the query was executed as a top-level statement (always true if pg_stat_statements.track is set to top)|
|queryid bigint||Hash code to identify identical normalized queries.|
|query text||Text of a representative statement|
|plans bigint||Number of times the statement was planned (if pg_stat_statements.track_planning is enabled, otherwise zero)|
|total_plan_time double precision||Total time spent planning the statement, in milliseconds (if pg_stat_statements.track_planning is enabled, otherwise zero)|
|min_plan_time double precision||Minimum time spent planning the statement, in milliseconds (if pg_stat_statements.track_planning is enabled, otherwise zero)|
A full list of statistics is available in the pg_stat_statements docs.
For more information on query optimization, check out the query performance guide.
Enable the extension#
- Go to the Database page in the Dashboard.
- Click on Extensions in the sidebar.
- Search for "pg_stat_statements" and enable the extension.
A common use for
pg_stat_statements is to track down expensive or slow queries. The
pg_stat_statements view contains a row for each executed query with statistics inlined. For example, you can leverage the statistics to identify frequently executed and slow queries against a given table.
select calls, mean_exec_time, max_exec_time, total_exec_time, stddev_exec_time, query, from pg_stat_statements where calls > 50 -- at least 50 calls and mean_exec_time > 2.0 -- averaging at least 2ms/call and total_exec_time > 60000 -- at least one minute total server time spent and query ilike '%user_in_organization%' -- filter to queries that touch the user_in_organization table order by calls desc
From the results, we can make an informed decision about which queries to optimize or index.
- Official pg_stat_statements documentation