Re: So, is COUNT(*) fast now?
От | Tom Lane |
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Тема | Re: So, is COUNT(*) fast now? |
Дата | |
Msg-id | 29572.1319222011@sss.pgh.pa.us обсуждение исходный текст |
Ответ на | Re: So, is COUNT(*) fast now? (Robert Haas <robertmhaas@gmail.com>) |
Ответы |
Re: So, is COUNT(*) fast now?
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Список | pgsql-hackers |
Robert Haas <robertmhaas@gmail.com> writes: > On Fri, Oct 21, 2011 at 2:08 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote: >> What this test case proves is that btree's overhead per index >> tuple touched is significantly more than the cost of the fastest path >> through HeapTupleSatisfiesMVCC, which I don't find surprising >> considering how much sweat has been expended on that code path over the >> years. > I think HeapTupleSatisfiesMVCC is probably being skipped anyway in > this case, since all the heap pages should be PD_ALL_VISIBLE. Proves my point ;-) ... you're comparing a code path that's been beat on for *years* with one that just got written. regards, tom lane
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