On Sat, 2007-01-27 at 21:44 +1100, Russell Smith wrote: > Guido Neitzer wrote: > > On 27.01.2007, at 00:35, Russell Smith wrote: > > > >> Guess 1 would be that your primary key is int8, but can't be certain > >> that is what's causing the problem. > > > > Why could that be a problem? > Before 8.0, the planner would not choose an index scan if the types were > different int8_col = const, int8_col = 4. > 4 in this example is cast to int4. int8 != int4. So the planner will > not choose an index scan. But, in 7.4 setting enable_seqscan off would not make it use that index. For the OP, the problem is likely either that the stats for the column are off, effective_cache_size is set too low, and / or random_page_cost is too high. there are other possibilities as well. FYI, I upgraded the server we use at work to scan a statistical db of our production performance, and the queries we run there, which take anywhere from a few seconds to 20-30 minutes, run much faster. About an hour after the upgrade I had a user ask what I'd done to the db to make it so much faster. The upgrade was 7.4 to 8.1 btw... still testing 8.2, and it looks very good.
