On Wed, 20 Feb 2019 at 10:49, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> What if we dropped that idea, and instead defined the plan tree as
> returning only the columns that are updated by SET, plus the row
> identity? It would then be the ModifyTable node's job to fetch the
> original tuple using the row identity (which it must do anyway) and
> form the new tuple by combining the updated columns from the plan
> output with the non-updated columns from the original tuple.
>
> DELETE would be even simpler, since it only needs the row identity
> and nothing else.
While I didn't look at the patch in great detail, I think this is how
Pavan must have made MERGE work for partitioned targets. I recall
seeing the tableoid being added to the target list and a lookup of the
ResultRelInfo by tableoid.
Maybe Pavan can provide more useful details than I can.
--
David Rowley http://www.2ndQuadrant.com/
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