| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | "Dann Corbit" <DCorbit(at)connx(dot)com> |
| Cc: | "Alvaro Herrera" <alvherre(at)commandprompt(dot)com>, pgsql-hackers(at)postgresql(dot)org, "PostgreSQL Performance" <pgsql-performance(at)postgresql(dot)org>, "Steve" <cheetah(at)tanabi(dot)org> |
| Subject: | Re: [HACKERS] choose_bitmap_and again (was Re: Strangely Variable Query Performance) |
| Date: | 2007-04-14 15:52:45 |
| Message-ID: | 4535.1176565965@sss.pgh.pa.us |
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| Lists: | pgsql-hackers pgsql-patches pgsql-performance |
"Dann Corbit" <DCorbit(at)connx(dot)com> writes:
> Instead of sorting, I suggest the quickselect() algorithm, which is
> O(n).
What for? Common cases have less than half a dozen entries. That is
not the place we need to be spending engineering effort --- what we
need to worry about is what's the choice algorithm, not implementation
details.
regards, tom lane
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