On 08/28/2013 12:10 AM, Pavel Stehule wrote: > > > 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
And you are perfectly ok to discard the results Actually it would be much more helpful to have "discard the results" syntax from client side, as in this case they take up network resources.
> > 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() > > 1,2 > 2 > 3,4 > > Procedure is a script (batch) moved to server side for better > performance and better reuse.
And you are perfectly ok to discard the results here as well
sure, depends how would to take a definition of procedure. Procedure is a classic procedure in PL/SQL - based on ADA procedures , or more like batch in T-SQL based on Sybase research, or some between in PSM in DB2. Every design has some advantage and disadvantage. But hardly to say what is a perfect design. I like a PL/SQL, but a procedures design (transaction control) is more obscure, than in T-SQL. DB2 procedures can use parameter list and can returns a status - it is a third design.
I don't propose procedures like syntactic sugar for current PostgreSQL behave. If we can support procedures one times, then we should to get a new functionality, that is not possible (or not simple possible) now.
In a function I do expect the result from select but I also expect that I can silently ignore the result.
> 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).
So you can ignore the result in a procedure (by just skipping / not assigning it on client) but not in a function ?
SQL function that is called from SELECT statement should to return only one result - without any side effect. It is a very good example, how clean and simple is using PostgreSQL functions that returns scalar or table, and how less clean and user friendly is usage functions that returns refcursors. I like a PostgreSQL design, that use a explicit or implicit transaction for every SELECT statement - and every function evaluation. It is simple, it is clean, and it is significant limit for some usage, where we can work more complexly with transactions. We must to break some code to more cliend-server calls. T-SQL is strict in this area, and disallow any side effect.
Can you point out some other languages which *require* you to store the result of a function call or have a special syntax/keyword when you do not want to store it ?
ADA is very strict about it.
Regards
Pavel
Cheer
-- Hannu Krosing PostgreSQL Consultant Performance, Scalability and High Availability 2ndQuadrant Nordic OÜ
From:
Robert Haas Date: Subject:
Re: ALTER SYSTEM SET command to change postgresql.conf parameters
(RE: Proposal for Allow postgresql.conf values to be changed via
SQL [review])
