| From: | Bruce Momjian <maillist(at)candle(dot)pha(dot)pa(dot)us> |
|---|---|
| To: | lockhart(at)alumni(dot)caltech(dot)edu (Thomas G(dot) Lockhart) |
| Cc: | vadim(at)sable(dot)krasnoyarsk(dot)su, hackers(at)postgreSQL(dot)org |
| Subject: | Re: [HACKERS] subselect |
| Date: | 1998-01-06 05:06:39 |
| Message-ID: | 199801060506.AAA11991@candle.pha.pa.us |
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| Lists: | pgsql-hackers |
>
> > BTW, note that for _expression_ subqueries (which are introduced without
> > IN, EXISTS, ALL, ANY - this follows Sybase' naming) - as in your examples -
> > we have to check that subquery returns single tuple...
>
> It might be nice to have a tuple-counting operation or query node (is this the right
> terminology?) which could be used to help implement EXISTS. It might help to
> re-implement the count(*) function also.
In the new code, count(*) picks a column from one of the tables to count
on.
--
Bruce Momjian
maillist(at)candle(dot)pha(dot)pa(dot)us
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