| From: | Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Vadim Mikheev <vadim(at)krs(dot)ru>, pgsql-hackers(at)postgreSQL(dot)org |
| Subject: | Re: [HACKERS] Idea for speeding up uncorrelated subqueries |
| Date: | 1999-08-06 05:11:23 |
| Message-ID: | 199908060511.BAA26768@candle.pha.pa.us |
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| Lists: | pgsql-hackers |
> Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us> writes:
> > Isn't it something that takes only a few hours to implement. We can't
> > keep telling people to us EXISTS, especially because most SQL people
> > think correlated queries are slower that non-correlated ones. Can we
> > just on-the-fly rewrite the query to use exists?
>
> I was just about to suggest exactly that. The "IN (subselect)"
> notation seems to be a lot more intuitive --- at least, people
> keep coming up with it --- so why not rewrite it to the EXISTS
> form, if we can handle that more efficiently?
Yes, we have the nice subselect feature. I just hate to see it not
completely finished, performance-wise.
--
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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