Thomas, RIGHT ON!
Sometimes I have seen this feature used to hide multiple round trips and intermediate result processing from the clients
Some others
is simply because the client is generating a predefined data structure that has little resemblance to the schema and this "feature" becomes convenient
Some others is "ad-hoc" tools that allow to see multiple datasets in the UI, etc...
Anyway I just saw this in the TODO list: (http://wiki.postgresql.org/wiki/Todo)
:
- PL/pgSQL stored procedure returning multiple result sets (SELECTs)?
- Proposal: real procedures again (8.4)
- http://archives.postgresql.org/pgsql-hackers/2010-09/msg00542.php
- Gathering specs and discussion on feature (post 9.1)
Does anybody know if any the committers are working on that list?
On Saturday, November 30, 2013 5:21 PM, Thomas Kellerer <spam_eater@xxxxxxx> wrote:
Alban Hertroys wrote on 30.11.2013 22:34:
>> - Multiple result sets
>
> Since you’re talking about procedures, you can’t possibly mean that those return multiple result sets?
Yes, basically something like this:
create procedure foobar()
begin
select * from table_1;
select * from table_2
end;
I know that at least SQL Server and MySQL can do that. Maybe others as well (Sybase most probably).
But I always failed do see the actual advantage of that because the results can't be "used" any further (e.g. in a JOIN or a subselect).
I also don't understand why having a single procedure doing a lot of stuff is better than having several procedures (or functions) doing one defined thing.
From a JDBC point of view the code simply asks the Statement whether it has any more result sets
and loops over this until all results are returned.
Thomas
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>> - Multiple result sets
>
> Since you’re talking about procedures, you can’t possibly mean that those return multiple result sets?
Yes, basically something like this:
create procedure foobar()
begin
select * from table_1;
select * from table_2
end;
I know that at least SQL Server and MySQL can do that. Maybe others as well (Sybase most probably).
But I always failed do see the actual advantage of that because the results can't be "used" any further (e.g. in a JOIN or a subselect).
I also don't understand why having a single procedure doing a lot of stuff is better than having several procedures (or functions) doing one defined thing.
From a JDBC point of view the code simply asks the Statement whether it has any more result sets
and loops over this until all results are returned.
Thomas
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