Re: [PATCH] Push limit to sort through a subquery

On Fri, Aug 25, 2017 at 7:35 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> I'm inclined to commit both of these after a little more testing and
>> self-review, but let me know if anyone else wants to review first.
>
> Looking through the first one, I wondered whether we needed to
> check for a qual expression on Gather or GatherMerge. It seems like
> it would be stupid to put a filter on that node rather than its
> children, but I see this in both nodeGather.c and nodeGatherMerge.c:
>
> /*
> * initialize child expressions
> */
> gatherstate->ps.qual =
> ExecInitQual(node->plan.qual, (PlanState *) gatherstate);
>
> It doesn't look like the qual is actually used anywhere in either node
> type. Am I right in thinking this is dead code?
>

I also think so. I think this was required in some initial versions
of gather node patch where we were thinking of having a single node
(instead of what we have now that Gather node and beneath there will
be partial scan node) to perform parallel scans.

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