Re: [HACKERS] modeling parallel contention (was: Parallel Append implementation)

On 5 May 2017 at 14:36, Andres Freund <andres@anarazel.de> wrote:
> I wonder how much doing the atomic ops approach alone can help, that
> doesn't have the issue that the work might be unevenly distributed
> between pages.

I wondered that too, since I though the barrier for making this change
would be lower by doing it that way.

I didn't manage to think of a way to get around the wrapping the
position back to 0 when synch-scans are involved.

i.e
parallel_scan->phs_cblock++;
if (parallel_scan->phs_cblock >= scan->rs_nblocks)
parallel_scan->phs_cblock = 0;

-- David Rowley                   http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services