On Tue, Jan 18, 2011 at 12:44 PM, Robert Haas <robertmh...@gmail.com> wrote: > On Tue, Jan 18, 2011 at 9:24 AM, Merlin Moncure <mmonc...@gmail.com> wrote: >> a few weeks back I hacked an experimental patch that removed the hint >> bit action completely. the results were very premature and/or >> incorrect, but my initial findings suggested that hint bits might not >> be worth the cost from performance standpoint. i'd like to see some >> more investigation in this direction before going with a complex >> application mechanism (although that would be beneficial vs the status >> quo). > > I think it's not very responsible to allege that hint bits aren't > providing a benefit without providing the patch that you used and the > tests that you ran. This is a topic that needs careful analysis, and > I think that saying "hint bits don't provide a benefit... maybe..." > doesn't do anything but confuse the issue. How about doing some tests > with the patch from my OP and posting the results? If removing hint > bits entirely doesn't degrade performance, then surely the > less-drastic approach I've taken here ought to be OK too. But in my > testing, it didn't look too good.
hm. well, I would have to agree on the performance hit -- I figure 5% scan penalty should be about the maximum you'd want to pay to get the i/o reduction. Odds are you're correct and I blew something...I'd be happy to test your patch. merlin -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
