rembFebruary 26, 2026: PostgreSQL 18.3, 17.9, 16.13, 15.17, and 14.22 Released!
Supported Versions: Current (18) / 17 / 16 / 15 / 14
Development Versions: devel
9.31. Statistics Information Functions #
PostgreSQL provides a function to inspect complex statistics defined using the CREATE STATISTICS command.
9.31.1. Inspecting MCV Lists #
pg_mcv_list_items
pg_mcv_list_items returns a set of records describing all items stored in a multi-column MCV list. It returns the following columns:
| Name | Type | Description |
|---|---|---|
index | integer | index of the item in the MCV list |
values | text[] | values stored in the MCV item |
nulls | boolean[] | flags identifying NULL values |
frequency | double precision | frequency of this MCV item |
base_frequency | double precision | base frequency of this MCV item |
The pg_mcv_list_items function can be used like this:
SELECT m.* FROM pg_statistic_ext join pg_statistic_ext_data on (oid = stxoid), pg_mcv_list_items(stxdmcv) m WHERE stxname = 'stts';
Values of the pg_mcv_list type can be obtained only from the pg_statistic_ext_data.stxdmcv column.
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