Re: So, is COUNT(*) fast now?
От | Tom Lane |
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Тема | Re: So, is COUNT(*) fast now? |
Дата | |
Msg-id | 20908.1319339688@sss.pgh.pa.us обсуждение исходный текст |
Ответ на | Re: So, is COUNT(*) fast now? (Robert Haas <robertmhaas@gmail.com>) |
Список | pgsql-hackers |
Robert Haas <robertmhaas@gmail.com> writes: > On Fri, Oct 21, 2011 at 3:55 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote: >> Robert Haas <robertmhaas@gmail.com> writes: >>> Anyhow, here's the scoop. On my desktop machine running F14, running >>> SELECT sum(1) FROM pgbench_accounts in a tight loop, 60 s worth of >>> oprofile data: >>> 176830 13.0801 postgres postgres ExecProject >> Hm, that's weird. In both these cases, I'd have expected that >> ExecProject would get optimized away thanks to selection of a physical >> tlist for the scan node. Wonder if that got broken ... > If it did, it looks like it wasn't recent. I set up the same test > case on my MacBook using REL9_1_STABLE and REL9_0_STABLE and set a > breakpoint on ExecProject(). Both back-branches appear to also call > ExecProject() for every tuple. Oh, the ExecProject calls are coming from advance_aggregates(). Move along, nothing to see here ... regards, tom lane
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