Re: Followup - expression (functional) index use in joins

Roger Ging <rging(at)paccomsys(dot)com> writes:
> Ran vacuum analyse on both program and logfile tables. Estimates are
> more in line with reality now,

And they are what now? You really can't expect to get useful help here
when you're being so miserly with the details ...

FWIW, I suspect you could force 7.4 to generate 7.3's plan by setting
enable_mergejoin to off (might have to also set enable_hashjoin to off,
if it then tries for a hash join). 7.3 could not even consider those
join types in this example, while 7.4 can. The interesting question
from my perspective is why the planner is guessing wrong about the
relative costs of the plans. EXPLAIN ANALYZE results with each type of
join forced would be useful to look at.

regards, tom lane