Re: Supporting MERGE on updatable views

hi.
Excellent work!  regress test passed! The code looks so intuitive!

doc/src/sgml/ref/create_view.sgml.
Do we need to add <<command>MERGE</command> for the following sentence?

If the view or any of its base
      relations has an <literal>INSTEAD</literal> rule that causes the
      <command>INSERT</command> or <command>UPDATE</command> command
to be rewritten, then
      all check options will be ignored in the rewritten query, including any
      checks from automatically updatable views defined on top of the relation
      with the <literal>INSTEAD</literal> rule.


in src/backend/executor/nodeModifyTable.c line 3800: ExecModifyTable
`
datum = ExecGetJunkAttribute(slot,resultRelInfo->ri_RowIdAttNo,&isNull);
.....
oldtupdata.t_data = DatumGetHeapTupleHeader(datum);
oldtupdata.t_len = HeapTupleHeaderGetDatumLength(oldtupdata.t_data);
`
In ExecGetJunkAttribute(slot,resultRelInfo->ri_RowIdAttNo,&isNull);

does resultRelInfo->ri_RowIdAttNo must be 1 to make sure
DatumGetHeapTupleHeader(datum) works?
(I am not familiar with this part.....)