The pg_statistic_ext system catalog table holds definitions of extended planner statistics. Each row in this catalog corresponds to a statistics object created with CREATE STATISTICS.

column type references description
stxrelid oid pg_class.oid  The table containing the columns described by this object
stxname name   The name of the statistics object
stxnamespace pg_namespace.oid   The object identifier of the namespace that contains this statistics object
stxowner oid pg_authid.oid  The owner of the statistics object
stxkeys int2vector pg_attribute.oid  An array of attribute numbers, indicating which table columns are covered by this statistics object; for example, a value of 1 3 would mean that the first and the third table columns are covered
stxkind char[]   An array containing codes for the enabled statistics kinds; valid values are: d for n-distinct statistics, f for functional dependency statistics, and m for most common values (MCV) list statistics

The pg_statistic_ext entry is filled in completely during CREATE STATISTICS, but the actual statistical values are not computed then. Subsequent ANALYZE commands compute the desired values and populate an entry in the pg_statistic_ext_data catalog.

Parent topic: System Catalogs Definitions

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