On Wed, 2006-09-27 at 10:26, Tobias Brox wrote: > [Scott Marlowe - Wed at 10:19:24AM -0500] > > So, by decreasing them, you should move away from nested loops then, > > right? Has that not worked for some reason? > > I want to move to nested loops, they are empirically faster in many of > our queries, and that makes sense since we've got quite big tables and > most of the queries only touch a small partition of the data. > > I've identified that moving any of the cost constants (including > random_page_cost) upwards gives me the right result, but I'm still wary > if this is the right thing to do. Even if so, what constants should I > target first? I could of course try to analyze a bit what constants > give the biggest impact. Then again, we have many more queries hitting > the database than the few I'm doing research into (and those I'm doing > research into is even very simplified versions of the real queries). Ahh, the other direction then. I would think it's safer to nudge these a bit than to drop random page cost to 1 or set effective_cache_size to 1000 etc... But I'm sure you should test the other queries and / or keep an eye on your database while running to make sure those changes don't impact other users.
