Re: Problems with "pg.dropped" column after upgrade 9.5 to 9.6

Michael Paquier <michael.paquier@gmail.com> writes:
> And one bisect later:
> commit: 3fc6e2d7f5b652b417fa6937c34de2438d60fa9f
> author: Tom Lane <tgl@sss.pgh.pa.us>
> date: Mon, 7 Mar 2016 15:58:22 -0500
> Make the upper part of the planner work by generating and comparing Paths

Yeah.  The reimplementation I did in createplan.c causes the planner to
generate a targetlist that seems valid in practice, but doesn't pass the
rather simplistic test in ExecCheckPlanOutput.  (The latter is expecting
a simple null Const corresponding to a dropped column, but what it's
getting is a Var that references a null Const one plan level down.)

Not sure whether it's reasonable to make the planner jump through extra
hoops here, or complicate the null-for-dropped-cols test in
ExecCheckPlanOutput, or just delete that as not really needed.

            regards, tom lane