Re: parallelize queries containing initplans

On Thu, Mar 16, 2017 at 2:34 AM, Kuntal Ghosh
<kuntalghosh(dot)2007(at)gmail(dot)com> wrote:
> On Tue, Mar 14, 2017 at 3:20 PM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>> Based on that idea, I have modified the patch such that it will
>> compute the set of initplans Params that are required below gather
>> node and store them as bitmap of initplan params at gather node.
>> During set_plan_references, we can find the intersection of external
>> parameters that are required at Gather or nodes below it with the
>> initplans that are passed from same or above query level. Once the set
>> of initplan params are established, we evaluate those (if they are not
>> already evaluated) before execution of gather node and then pass the
>> computed value to each of the workers. To identify whether a
>> particular param is parallel safe or not, we check if the paramid of
>> the param exists in initplans at same or above query level. We don't
>> allow to generate gather path if there are initplans at some query
>> level below the current query level as those plans could be
>> parallel-unsafe or undirect correlated plans.
>
> I would like to mention different test scenarios with InitPlans that
> we've considered while developing and testing of the patch.
>

Thanks a lot Kuntal for sharing different test scenarios.
Unfortunately, this patch doesn't received any review till now, so
there is no chance of making it in to PostgreSQL-10. I have moved
this to next CF.

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