> On Fri, Feb 1, 2019 at 8:24 PM Jesper Pedersen <jesper.pedersen@redhat.com> wrote: > > Dmitry and I will look at this and take it into account for the next > version.
In the meantime, just to not forget, I'm going to post another version with a fix for cursor fetch backwards, which was crashing before.
This version of the patch can return the wrong answer.
create index on pgbench_accounts (bid, aid);
begin; declare c cursor for select distinct on (bid) bid, aid from pgbench_accounts order by bid, aid;
fetch 2 from c;
bid | aid
-----+---------
1 | 1
2 | 100,001
fetch backward 1 from c;
bid | aid
-----+---------
1 | 100,000
Without the patch, instead of getting a wrong answer, I get an error:
ERROR: cursor can only scan forward
HINT: Declare it with SCROLL option to enable backward scan.
If I add "SCROLL", then I do get the right answer with the patch.