On Mon, Jun 13, 2016 at 10:36 PM, Tom Lane <t...@sss.pgh.pa.us> wrote:
> Robert Haas <robertmh...@gmail.com> writes:
> > On Mon, Jun 13, 2016 at 11:02 AM, Tom Lane <t...@sss.pgh.pa.us> wrote:
> >> BTW, decent regression tests could be written without the need to
> >> enormous tables if the minimum rel size in create_plain_partial_paths()
> >> could be configured to something less than 1000 blocks.  I think it's
> >> fairly crazy that that arbitrary constant is hard-wired anyway.  Should
> >> we make it a GUC?
> > That was proposed before, and I didn't do it mostly because I couldn't
> > think of a name for it that didn't sound unbelievably corny.
> min_parallel_relation_size, or min_parallelizable_relation_size, or
> something like that?

You are right that such a variable will make it simpler to write tests for
parallel query.  I have implemented such a guc and choose to keep the name
as min_parallel_relation_size.  One thing to note is that in function
create_plain_partial_paths(), curently it is using PG_INT32_MAX/3 for
parallel_threshold to check for overflow, I have changed it to INT_MAX/3 so
as to be consistent with guc.c.  I am not sure if it is advisable to use
PG_INT32_MAX in guc.c as other similar parameters use INT_MAX.

With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com

Attachment: min_parallel_relation_size_v1.patch
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