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9.30. Statistics Information Functions

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

9.30.1. 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.