Re: procedures and plpgsql PERFORM

On Thu, Dec 14, 2017 at 11:56 AM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
>
>
> 2017-12-14 18:33 GMT+01:00 Merlin Moncure <mmoncure(at)gmail(dot)com>:
>>
>> On Thu, Dec 14, 2017 at 10:46 AM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
>> wrote:
>> >
>> >
>> > 2017-12-14 17:10 GMT+01:00 David G. Johnston
>> > <david(dot)g(dot)johnston(at)gmail(dot)com>:
>> >>
>> >> On Thu, Dec 14, 2017 at 8:22 AM, Merlin Moncure <mmoncure(at)gmail(dot)com>
>> >> wrote:
>> >>>
>> >>> On Thu, Dec 14, 2017 at 8:38 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> >>> > Ashutosh Bapat <ashutosh(dot)bapat(at)enterprisedb(dot)com> writes:
>> >>> >> We allow a function to be invoked as part of PERFORM statement in
>> >>> >> plpgsql
>> >>> >> ...
>> >>> >> But we do not allow a procedure to be invoked this way
>> >>> >
>> >>> >> Procedures fit that category and like functions, I think, we should
>> >>> >> allow them be invoked directly without any quoting and CALL
>> >>> >> decoration.
>> >>> >
>> >>> > How is that going to work? What if the procedure tries to commit
>> >>> > the
>> >>> > current transaction?
>> >>> >
>> >>> > IOW, this is not merely a syntactic-sugar question.
>> >>>
>> >>> BTW, We've already come to (near-but good enough) consensus that
>> >>> PERFORM syntax is really just unnecessary, and I submitted a patch to
>> >>> make it optional (which I really need to dust off and complete).
>> >>
>> >>
>> >> Except right now PERFORM doesn't exist in SQL and is a pl/pgsql keyword
>> >> to
>> >> specify a specific limited form of the SQL SELECT command. CALL is an
>> >> SQL
>> >> command. I don't see any real upside to allowing pl/pgsql to accept
>> >> omission of the command tag while SQL cannot - at least not without a
>> >> use-case describe why such syntax would be beneficial. And likely
>> >> those use
>> >> cases would revolve around some looping variant as opposed to a single
>> >> stand-alone, result-less, CALL.
>> >>
>> >> If we do keep "PERFORM" in the pl/pgsql vocab I'd consider the
>> >> following
>> >> enhancement:
>> >> PERFORM func() => SELECT func()
>> >> PERFORM proc() => CALL proc()
>> >
>> >
>> > I don't like this idea - functions are not procedures - can be nice if
>> > it
>> > will be visible.
>>
>> We need to get rid of PERFORM ASAP. Agree that we need to not obfuscate
>> CALL.
>
> If we have a procedures, then functions without returned values lost a sense
> - and I don't see any changes with PERFORM necessary.

I don't think the presence of procedures really changes the thinking
here. Having to simulate procedures with void returning functions
wasn't really the point; it's an annoying syntax departure from SQL
for little benefit other than assuming the users are wrong when they
are not explicitly capturing the result..

the topic was heavily discussed:
https://www.postgresql.org/message-id/CAHyXU0zYbeT-FzuonaaycbS9Wd8d5JO%2B_niAygzYtv5FMdx4rg%40mail.gmail.com

merlin