Re: [HACKERS] Why not sub-selects in targetlists? - Mailing list pgsql-hackers

From Tom Lane
Subject Re: [HACKERS] Why not sub-selects in targetlists?
Date
Msg-id 5650.936025452@sss.pgh.pa.us
Whole thread Raw
In response to Re: [HACKERS] Why not sub-selects in targetlists?  (Vadim Mikheev <vadim@krs.ru>)
List pgsql-hackers
Vadim Mikheev <vadim@krs.ru> writes:
> Tom Lane wrote:
>> For some reason we currently support sub-SELECT expressions only
>> in WHERE and HAVING clauses, not in the target list of a SELECT.
>> Does anyone know why this is?

> As usual, I just hadn't time to do more than it's done for
> 6.3.X -:) Subselects were not in my TODO list, I made base
> implementation because of there were many requests for them.

OK, I'll see about adding the missing transformations in the
planner.  Shouldn't be hard.

> BTW, please don't forget subselects in FROM.

That seems to be a considerably bigger task :-(
        regards, tom lane


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