On Tue, Jan 27, 2015 at 08:02:37AM +0100, Daniel Bausch wrote: > Hi PG devs! > > Tom Lane <t...@sss.pgh.pa.us> writes: > > >> Wait for first IO, issue second IO request > >> Compute > >> Already have second IO request, issue third > >> ... > > > >> We'd be a lot less sensitive to IO latency. > > > > It would take about five minutes of coding to prove or disprove this: > > stick a PrefetchBuffer call into heapgetpage() to launch a request for the > > next page as soon as we've read the current one, and then see if that > > makes any obvious performance difference. I'm not convinced that it will, > > but if it did then we could think about how to make it work for real. > > Sorry for dropping in so late... > > I have done all this two years ago. For TPC-H Q8, Q9, Q17, Q20, and Q21 > I see a speedup of ~100% when using IndexScan prefetching + Nested-Loops > Look-Ahead (the outer loop!). > (On SSD with 32 Pages Prefetch/Look-Ahead + Cold Page Cache / Small RAM)
Would you be so kind as to pass along any patches (ideally applicable to git master), tests, and specific measurements you made? Cheers, David. -- David Fetter <da...@fetter.org> http://fetter.org/ Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter Skype: davidfetter XMPP: david.fet...@gmail.com Remember to vote! Consider donating to Postgres: http://www.postgresql.org/about/donate -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
