"Mike Quinn" <mquinn@co.merced.ca.us> writes:
> -- The order of fields around the "=" in the WHERE conditions
> -- affects the query plan.
BTW, what's the datatype(s) of the join columns? The behavior looks
consistent with the idea that the planner doesn't think it can commute
the join conditions, which would be a bug/omission in the set of
operators existing for the datatype(s). I believe we've got commutators
for all the standard '=' operators, but a contrib or third-party
datatype might be missing this.
regards, tom lane