Re: UPDATE of partition key

On Fri, Jun 16, 2017 at 5:36 AM, Amit Khandekar <amitdkhan(dot)pg(at)gmail(dot)com> wrote:
> There is another issue I discovered. The row-movement works fine if
> the destination leaf partition has different attribute ordering than
> the root : the existing insert-tuple-routing mapping handles that. But
> if the source partition has different ordering w.r.t. the root, it has
> a problem : there is no mapping in the opposite direction, i.e. from
> the leaf to root. And we require that because the tuple of source leaf
> partition needs to be converted to root partition tuple descriptor,
> since ExecFindPartition() starts with root.
>
> To fix this, I have introduced another mapping array
> mtstate->mt_resultrel_maps[]. This corresponds to the
> mtstate->resultRelInfo[]. We don't require per-leaf-partition mapping,
> because the update result relations are pruned subset of the total
> leaf partitions.

Hi Amit & Amit,

Just a thought: If I understand correctly this new array of tuple
conversion maps is the same as mtstate->mt_transition_tupconv_maps in
my patch transition-tuples-from-child-tables-v11.patch (hopefully soon
to be committed to close a PG10 open item). In my patch I bounce
transition tuples from child relations up to the named relation's
triggers, and in this patch you bounce child tuples up to the named
relation for rerouting, so the conversion requirement is the same.
Perhaps we could consider refactoring to build a common struct member
on demand for the row movement patch at some point in the future if it
makes the code cleaner.

--
Thomas Munro
http://www.enterprisedb.com