Stuart Bishop <stuart(at)stuartbishop(dot)net> writes:
> We also found this problem did not occur on one of our staging
> systems, which had a default statistics target of 100. Lowering the
> statistics on the relavant columns from 1000 to 100 and reanalyzing
> made the overhead unnoticeable.
eqjoinsel() is O(N^2) in the number of entries in the MCV lists.
I wouldn't expect this to be an issue unless comparison is pretty
expensive, but maybe those are string not integer columns?
> Thoughts on IRC was this might be a regression in 8.4.9, but I haven't
> got earlier versions to test with at the moment.
eqjoinsel has worked like that for many years. Are you claiming you
didn't see this behavior in a prior release? If so, which one?
regards, tom lane