| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Martijn van Oosterhout <kleptog(at)svana(dot)org> |
| Cc: | Markus Schiltknecht <markus(at)bluegap(dot)ch>, pgsql-general(at)postgresql(dot)org |
| Subject: | Re: rules: evaluate inputs in advance |
| Date: | 2006-05-14 16:23:33 |
| Message-ID: | 14284.1147623813@sss.pgh.pa.us |
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| Lists: | pgsql-general |
Martijn van Oosterhout <kleptog(at)svana(dot)org> writes:
> Well, I notice that the SQL standard defines something called WITH, so
> what you want is something like:
> WITH OLD AS ( SELECT blah )
> DO
> ( UPDATE <rule1>
> ; DELETE <rule2> )
I think it'd be a mistake to assume that WITH would fix Markus'
complaint. I haven't studied the spec in detail but I think that WITH
acts largely like a macro too. It certainly doesn't have the behavior
of "evaluate this just once", as one of the prime uses for it is in
recursive query definition.
regards, tom lane
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