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Re: Can't use WITH in a PERFORM query in PL/pgSQL?

From: Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Valentine Gogichashvili <valgog(at)gmail(dot)com>, pgsql-bugs(at)postgresql(dot)org, Merlin Moncure <mmoncure(at)gmail(dot)com>
Subject: Re: Can't use WITH in a PERFORM query in PL/pgSQL?
Date: 2011-10-20 21:25:28
Message-ID: CAFj8pRAyfES9HmsycX+u5SghVqgqBPyPszX9s3YEMWRTSwN+4A@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-bugs
2011/10/20 Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>:
> Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> writes:
>> I didn't design a PERFORM statement. There is two views - somebody
>> from sybase's family know so SELECT without into is forwarded to
>> client. This functionality is missing on Oracle's family. Is true so
>> PERFORM statement is strange,  but maybe it's open door for sybase's
>> functionality that was not implemented ever.
>
> I cannot imagine that we'd ever make SELECT inside a plpgsql function
> act like that.  Functions have no business directly transmitting
> information to the client; if they tried, they'd most likely just break
> the FE/BE protocol.
>
> There might be use for such a thing in a hypothetical "real stored
> procedure language" where the code is executing in a context entirely
> different from what Postgres functions run in ... but that language
> would be something different from plpgsql.
>
> I grant the argument that people coming from Sybase-ish DBs might be
> confused by this; but the current arrangement is also confusing lots
> of people, so I don't think that argument has all that much weight.

I agree with you you in almost all - Sybase-ish SELECT has sense for
procedures only (in PL/pgSQL) - In SQL/PSM is natural for table
functions. I disagree with Merlin or Valentine from one reason - What
is sense of SELECT, that has not processed result? Is it correct from
language design perspective?

I can do a write a query with sense - like SELECT fx(i) FROM
generate_series(1,1000)  or query without sense - like SELECT 1 FROM
generate_series(1,1000) - when we enable a SELECT without INTO. And
there is next question - is first select a good idea - from
readability perspective - in PL/pgSQL - is not better to use a SQL
language??

Regards

Pavel Stehule

p.s. other question is implementation of PERFORM - that is it a just
SELECT synonym,


>
>                        regards, tom lane
>

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