Re: executor relation handling - Mailing list pgsql-hackers

From Amit Langote
Subject Re: executor relation handling
Date
Msg-id CA+HiwqHQQPrN5yqC=EUrgtwT-d1pR5oWA1fLB3ZKtdGBy_rg8w@mail.gmail.com
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In response to Re: executor relation handling  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
On Tue, Oct 9, 2018 at 11:07 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
> Amit Langote <Langote_Amit_f8@lab.ntt.co.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


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