Dmitry Tkach <dmitry@openratings.com> writes:
> I now have the same problem with it, but the other way around - the
> query with a condition on a runs quickly, and one with a condition on b
> does not... and the query plans are the same, and have a as outer table...
Hm. You know, I wonder whether the query plans really are the same.
One of the reasons why 7.3 and later show the qual conditions is that
it was too easy to fall into the trap of assuming that plans of the same
structure had the same conditions. Try doing "explain verbose" and look
to see if the plans look the same at that level of detail.
regards, tom lane