51.51. pg_statistic_ext

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

Table 51.51. pg_statistic_ext Columns

stxrelidoidpg_class.oidTable containing the columns described by this object
stxnamename Name of the statistics object
stxnamespaceoidpg_namespace.oid The OID of the namespace that contains this statistics object
stxowneroidpg_authid.oidOwner of the statistics object
stxkeysint2vectorpg_attribute.attnum 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
stxkindchar[]  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.