Re: Scrolling/Updating Cursors

On Nov 19, 2013, at 6:33 PM, Kevin Wooten <kdubb(at)me(dot)com> wrote:

> My apologies for posting what is almost certainly somewhat of a repeat question but I have searched and attempted everything I can think of and cannot figure it out myself.
>
> The basic question is… Is it possible to get a scrollable cursor that, within a transaction, can insert/update/delete rows and see those changes?
>
> Why you ask? Because I am implementing the JDBC 4.1 spec and it (optionally) provides this ability and I’d like to provide it if possible. I thought just using a scrollable cursor with the isolation-level set to repeatable-read would do the trick but it still seems to see no changes (inserts/updates/deletes).
>
> Effectively I want roughly this sequence of events to work.
>
> CREATE TABLE test (val text);
>
> BEGIN; # Could include ISOLATION LEVEL REPEATABLE READ
>
> DECLARE c1 CURSOR FOR SELECT * FROM test;
>
> FETCH ABSOLUTE 1; # Returns No Row
>
> INSERT INTO test VALUES (‘1');
> INSERT INTO test VALUES (‘2');
> INSERT INTO test VALUES (‘3');
>
> FETCH ABSOLUTE 1; # Returns “1”
> FETCH NEXT: # Returns “2"
> DELETE FROM test WHERE CURRENT OF c1; # Deletes “2”
>
> FETCH ABSOLUTE 1; # Returns “1”
> FETCH NEXT; # Returns “3”
> UPDATE test SET val=‘4' WHERE CURRENT OF c1;
> FETCH RELATIVE 0; # Returns “4”
>
> COMMIT;
>
> Thanks!
>
> -kw
>

Should I take silence to mean this cannot be done? Or should I send to -hackers?