| From: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | PostgreSQL-development <pgsql-hackers(at)postgreSQL(dot)org> |
| Subject: | Re: [HACKERS] Re: subquery performance and EXISTS |
| Date: | 1999-12-29 21:20:38 |
| Message-ID: | 199912292120.QAA11403@candle.pha.pa.us |
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| Lists: | pgsql-hackers |
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> > Tom, does it still look easy to change, and if so, can you change it to
> > hash?
>
> We could probably do it, but there is the little problem that hash joins
> only work for a very limited set of data types and operators. This
> wouldn't be a complete solution on its own.
How hard would it be to have the EXISTS be done automatically? The
performance problem for subqueries has bothered me for two years now. I
don't think I know enough to fix it, though.
--
Bruce Momjian | http://www.op.net/~candle
maillist(at)candle(dot)pha(dot)pa(dot)us | (610) 853-3000
+ If your life is a hard drive, | 830 Blythe Avenue
+ Christ can be your backup. | Drexel Hill, Pennsylvania 19026
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