pg_statistic_ext
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 |
|---|---|---|---|
oid | oid | The object ID | |
stxrelid | oid | pg_class.oid | The table containing the columns described by this object |
stxname | name | The name of the statistics object | |
stxnamespace | oid | pg_namespace.oid | |
stxowner | oid | pg_authid.oid | The owner of the statistics object |
stxstattarget | integer | Statistics target for this extended statistics object. Controls the level of detail of statistics collected by ANALYZE for this object. A value of -1 indicates that the statistics targets of the referenced columns or the system default statistics target should be used. | |
stxkeys | ARRAY | 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 | ARRAY | 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 | |
stxexprs | pg_node_tree | If the statistics object is defined on expressions, this column stores the parse tree representation of those expressions. If the statistics object is only defined on simple columns (via stxkeys), this field will be NULL. |
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.
