Re: [HACKERS] UPDATE of partition key

While rebasing my patch for the below recent commit, I realized that a
similar issue exists for the uptate-tuple-routing patch as well :

commit 78a030a441966d91bc7e932ef84da39c3ea7d970
Author: Tom Lane <tgl@sss.pgh.pa.us>
Date:   Mon Jun 12 23:29:44 2017 -0400
   Fix confusion about number of subplans in partitioned INSERT setup.

The above issue was about incorrectly using 'i' in
mtstate->mt_plans[i] during handling WITH CHECK OPTIONS in
ExecInitModifyTable(), where 'i' was actually meant to refer to the
positions in mtstate->mt_num_partitions. Actually for INSERT, there is
only a single plan element in mtstate->mt_plans[] array.

Similarly, for update-tuple routing, we cannot use
mtstate->mt_plans[i], because 'i' refers to position in
mtstate->mt_partitions[] , whereas mtstate->mt_plans is not at all in
order of mtstate->mt_partitions; in fact mt_plans has only the plans
that are to be scanned on pruned partitions; so it can well be a small
subset of total partitions.

I am working on an updated patch to fix the above.