Franck Routier <franck.routier@axege.com> writes:
> Le 05/04/2013 16:17, Tom Lane a �crit :
>> What have you got the statistics targets set to in this database?
> Ok, the problem definitely comes from the default_statistics_target
> which is obviously too high on the database.
Yeah, eqjoinsel() is O(N^2) in the lengths of the MCV lists, in the
worst case where there's little overlap in the list memberships.
The actual cost would depend a lot on the specific column datatypes.
Not sure about your report that re-analyzing with the same stats target
made a significant difference. It might have been a matter of chance
variation in the sampled MCV list leading to more or fewer matches.
regards, tom lane