3rd October 2019: PostgreSQL 12 Released!
Supported Versions: Current (12)
Development Versions: devel

9.29. Statistics Information Functions

PostgreSQL provides a function to inspect complex statistics defined using the CREATE STATISTICS command.

9.29.1. Inspecting MCV Lists

pg_mcv_list_items returns a list of all items stored in a multi-column MCV list, and returns the following columns:

Name Type Description
index int 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 can be obtained only from the pg_statistic_ext_data.stxdmcv column.

Submit correction

If you see anything in the documentation that is not correct, does not match your experience with the particular feature or requires further clarification, please use this form to report a documentation issue.