On Sat, Mar 4, 2017 at 12:23 AM, Robert Haas <robertmhaas@gmail.com> wrote:
>> I guess that the workMem scaling threshold thing could be
>> min_parallel_index_scan_size, rather than min_parallel_relation_size
>> (which we now call min_parallel_table_scan_size)?
>
> No, it should be based on min_parallel_table_scan_size, because that
> is the size of the parallel heap scan that will be done as input to
> the sort.
I'm talking about the extra thing we do to prevent parallelism from
being used when per-worker workMem is excessively low. That has much
more to do with projected index size than current heap size.
I agree with everything else you've said, I think.
--
Peter Geoghegan