The catalog pg_statistic_ext_data holds data for extended planner statistics defined in pg_statistic_ext. Each row in this catalog corresponds to a statistics object created with CREATE STATISTICS.
Normally there is one entry, with stxdinherit
=
false
, for each statistics object that has been analyzed.
If the table has inheritance children or partitions, a second entry with
stxdinherit
= true
is also created.
This row represents the statistics object over the inheritance tree, i.e.,
statistics for the data you'd see with
SELECT * FROM
,
whereas the table
*stxdinherit
= false
row
represents the results of
SELECT * FROM ONLY
.
table
Like pg_statistic, pg_statistic_ext_data should not be readable by the public, since the contents might be considered sensitive. (Example: most common combinations of values in columns might be quite interesting.) pg_stats_ext is a publicly readable view on pg_statistic_ext_data (after joining with pg_statistic_ext) that only exposes information about tables the current user owns.
Table 51.53. pg_statistic_ext_data Columns
Column Type Description |
---|
Extended statistics object containing the definition for this data |
If true, the stats include values from child tables, not just the values in the specified relation |
N-distinct counts, serialized as pg_ndistinct type |
Functional dependency statistics, serialized as pg_dependencies type |
MCV (most-common values) list statistics, serialized as pg_mcv_list type |
Per-expression statistics, serialized as an array of pg_statistic type |