On Thu, Mar 9, 2017 at 8:43 AM, Robert Haas <robertmh...@gmail.com> wrote: > On Wed, Mar 8, 2017 at 2:30 PM, Alvaro Herrera <alvhe...@2ndquadrant.com> > wrote: >> Not really -- it's a bit slower actually in a synthetic case measuring >> exactly the slowed-down case. See >> https://www.postgresql.org/message-id/cad__ougk12zqmwwjzim-yyud1y8jmmy6x9yectnif3rpp6h...@mail.gmail.com >> I bet in normal cases it's unnoticeable. If WARM flies, then it's going >> to provide a larger improvement than is lost to this. > > Hmm, that test case isn't all that synthetic. It's just a single > column bulk update, which isn't anything all that crazy, and 5-10% > isn't nothing. > > I'm kinda surprised it made that much difference, though. >
I think it is because heap_getattr() is not that cheap. We have noticed the similar problem during development of scan key push down work [1]. [1] - https://commitfest.postgresql.org/12/850/ -- With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
