Re: PL/pgSQL PERFORM with CTE - Mailing list pgsql-hackers
| From | Pavel Stehule |
|---|---|
| Subject | Re: PL/pgSQL PERFORM with CTE |
| Date | |
| Msg-id | CAFj8pRC3-Zxt1OFvpy3k_HMF3u78-f-xFt+0CKA0WAosAUbLvA@mail.gmail.com Whole thread Raw |
| In response to | Re: PL/pgSQL PERFORM with CTE ("David E. Wheeler" <david@justatheory.com>) |
| Responses |
Re: PL/pgSQL PERFORM with CTE
("David E. Wheeler" <david@justatheory.com>)
Re: PL/pgSQL PERFORM with CTE (Hannu Krosing <hannu@2ndQuadrant.com>) Re: PL/pgSQL PERFORM with CTE (Robert Haas <robertmhaas@gmail.com>) |
| List | pgsql-hackers |
2013/8/27 David E. Wheeler <david@justatheory.com>
2
3,4
On Aug 27, 2013, at 1:36 PM, Pavel Stehule <pavel.stehule@gmail.com> wrote:That does not make it a bad idea. Let me summarize:
> I agree with David that we should use some new syntax to specify
> return-results-directly-to-client, assuming we ever get any such
> functionality. It seems like a pretty bad choice of default behavior,
> which is essentially what you're saying it should be.
>
> this functionality should be disabled in functions. This can be allowed only for procedures started by CALL statements. I don't propose it for functions.
I propose to remove the requirement to use PERFORM to execute queries for which the result should be discarded. It should instead be implicit that results are discarded unless you capture them or return them.
You propose to continue requiring PERFORM to execute queries for which the result should be discarded. This is so that, in the future, SQL statements can implicitly return to the caller.
That sound about right to you?
I *really* dislike the idea that some SQL execution implicitly returns from a PL/pgSQL function or procedure. That just seems too magical. I strongly prefer that the scope of the code executed in a function or procedure be limited to the scope of the function or procedure itself, and only return data to the caller if I explicitly tell it to. Much less magical, IMHO.
what is magical?
Stored procedures - we talk about this technology was a originally simple script moved from client side to server side.
so if I write on client side
BEGIN;
SELECT 1,2;
SELECT 2;
SELECT 3,4;
END;
then I expect results
1,2
2
3,4
1,2
2
3,4
Procedure is some batch moved and wrapped on server side
CREATE PROCEDURE foo()
BEGIN
SELECT 1,2;
SELECT 2;
SELECT 3,4
END;
And is not strange expect a result
CALL foo()
1,22
3,4
Procedure is a script (batch) moved to server side for better performance and better reuse.
You should not thinking about procedures like void functions, because it is a little bit different creature - and void functions is significantly limited in functionality.
My proposal is consistent - no result goes to /dev/null without special mark. It is disabled (in function) or it goes to client (in procedures).
Regards
Pavel
Best,
David
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