Re: committing inside cursor loop

From: Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>
To: Ildus Kurbangaliev <i(dot)kurbangaliev(at)postgrespro(dot)ru>
Cc: pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: committing inside cursor loop
Date: 2018-03-13 15:08:36
Message-ID: 4ab5df79-140a-23f8-879a-94d5c4978be3@2ndquadrant.com
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On 3/6/18 07:48, Ildus Kurbangaliev wrote:
> Although as was discussed before it seems inconsistent without ROLLBACK
> support. There was a little discussion about it, but no replies. Maybe
> the status of the patch should be changed to 'Waiting on author' until
> the end of discussion.

I'm wondering what the semantics of it should be.

For example, consider this:

drop table test1;
create table test1 (a int, b int);
insert into test1 values (1, 11), (2, 22), (3, 33);

do
language plpgsql
$$
declare
x int;
begin
for x in update test1 set b = b + 1 where b > 20 returning a loop
raise info 'x = %', x;
if x = 2 then
rollback;
end if;
end loop;
end;
$$;

The ROLLBACK call in the first loop iteration undoes the UPDATE command
that drives the loop. Is it then sensible to continue the loop?

--
Peter Eisentraut http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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