Re: executor relation handling

On Tue, Oct 9, 2018 at 11:07 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>
> Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp> writes:
> > On 2018/10/08 3:55, Tom Lane wrote:
> >> I didn't like the idea of unifying ModifyTable.nominalRelation with
> >> the partition root info. Those fields serve different masters ---
> >> nominalRelation, at least in its original intent, is only meant for
> >> use of EXPLAIN and might have nothing to do with what happens at
> >> execution. So even though unifying them would work today, we might
> >> regret it down the line. Instead I left that field alone and added
> >> a separate rootRelation field to carry the partition root RT index,
> >> which ends up being the same number of fields anyway since we don't
> >> need a flag for is-the-nominal-relation-a-partition-root.
>
> > Thanks for pushing that. I'd also named it 'rootRelation' in my original
> > patch before David had objected to calling it that, because a command may
> > not specify the "actual" root of a partition tree; it could be a non-root
> > partitioned table. He'd suggested 'partitionedTarget' for the new field
> > [1], stressing the "target" part. Maybe, 'rootRelation' isn't too
> > confusing though.
>
> Well, it's the root so far as the current query is concerned --- we do not
> take any semantic account of partitioning levels that might exist above
> the table named in the query, do we?

We don't, and I personally agree with the reasoning behind calling it
rootRelation.

Thanks,
Amit