stxkind : An array containing codes for the enabled statistics kinds; valid values are: d for n-distinct statistics, f for functional dependency statistics
select distinct stxkind from pg_statistic_ext ;
return:
stxkind --------- {d} {m} {f} {e} (4 rows)
I guess e for expression statistics. Since I create the following statistics object.
create statistics flight_expr1 on( extract (month from scheduled_departure at time zone 'Asia/Kolkata') ) from flights;
select stxkind from pg_statistic_ext where stxname = 'flight_expr';
and it return e.
But I am not sure what does m mean?
It would be better to full explain all these four elements in the doc.
stxkind : An array containing codes for the enabled statistics kinds; valid values are: d for n-distinct statistics, f for functional dependency statistics