Postgresql 中文操作指南

9.30. Statistics Information Functions #

PostgreSQL 提供了一个函数来检查使用 CREATE STATISTICS 命令定义的复杂统计信息。

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

9.30.1. Inspecting MCV Lists #

pg_mcv_list_items ( pg_mcv_list ) → setof record

pg_mcv_list_items 返回一组记录，描述存储在多列 MCV 列表中的所有项目。它将返回下列列：

pg_mcv_list_items returns a set of records describing all items stored in a multi-column MCV list. It returns the following columns:

pg_mcv_list_items 函数可用以下方式使用：

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';

pg_mcv_list 类型的值只能从 pg_statistic_ext_data.stxdmcv 列中获得。

Values of the pg_mcv_list type can be obtained only from the pg_statistic_ext_data.stxdmcv column.