> On Wed, Jul 10, 2019 at 4:52 PM Floris Van Nee <florisvannee@optiver.com> wrote:
>
> > Thanks for testing! Could you provide a test case to show what exactly is the
> > problem?
>
> create table a (a int, b int, c int);
> insert into a (select vs, ks, 10 from generate_series(1,5) vs, generate_series(1, 10000) ks);
> create index on a (a,b);
> analyze a;
>
> set enable_indexskipscan=1; // setting this to 0 yields different results
> set random_page_cost=1;
> explain SELECT DISTINCT ON (a) a,b FROM a;
>
> BEGIN;
> DECLARE c SCROLL CURSOR FOR SELECT DISTINCT ON (a) a,b FROM a;
>
> FETCH FROM c;
> FETCH BACKWARD FROM c;
>
> FETCH 6 FROM c;
> FETCH BACKWARD 6 FROM c;
>
> FETCH 6 FROM c;
> FETCH BACKWARD 6 FROM c;
>
> END;
Ok, give me a moment, I'll check.
