Re: Set generating functions and subqueries

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Markus Schaber <schabi(at)logix-tt(dot)com>
Cc: PostgreSQL SQL List <pgsql-sql(at)postgresql(dot)org>
Subject: Re: Set generating functions and subqueries
Date: 2006-03-13 14:57:39
Message-ID: 7169.1142261859@sss.pgh.pa.us
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Markus Schaber <schabi(at)logix-tt(dot)com> writes:
> Tom Lane wrote:
>> The fact that the other form is even allowed is more of a holdover from
>> PostQUEL than something we have consciously decided is a good idea.
>> (IMHO it's actually a fairly *bad* idea, because it does not work nicely
>> when there's more than one SRF in the same targetlist.) It'll probably
>> get phased out someday, if we can find a way to replace the
>> functionality. I seem to recall speculating that SQL2003's LATERAL
>> tables might do the job.

> AFAICS, it can be replaced with JOINs:

Not really; the case where joins don't help is where you want to
generate the SRF's output for each of the values appearing in a table.
There's an example in "SQL Functions Returning Sets" in the manual:
http://www.postgresql.org/docs/8.1/static/xfunc-sql.html#AEN31646

regards, tom lane

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