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

Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> writes:
> On Fri, Aug 25, 2017 at 7:35 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> 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:
>>
>> 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.

Thanks for confirming. I'll replace that with something like
Assert(!node->plan.qual). I have some other code-review-ish
fixes to do in nodeGatherMerge, too.

regards, tom lane