PostgreSQL
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 of the item in the MCV list |
|
|
values stored in the MCV item |
|
|
flags identifying |
|
|
frequency of this MCV item |
|
|
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.
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|---|---|---|
9.28. Event Trigger Functions |
Chapter 10. Type Conversion |
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