Re: Clause accidentally pushed down ( Possible bug in Making Vars outer-join aware)

On Thu, Mar 2, 2023 at 11:27 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:

> What's feeling like it might be the best thing is to go ahead and
> syntactically convert to the second form of identity 3 as soon as
> we've determined it's applicable, so that upper C Vars are always
> marked with both OJ relids.  Not sure how much work is involved
> there.


I'm thinking something that once we've determined identity 3 applies in
make_outerjoininfo we record information about how to adjust relids for
upper quals and store this info in all upper JoinTreeItems.  Then
afterwards in distribute_qual_to_rels we check all this info stored in
current JoinTreeItem and adjust relids for the qual accordingly.

The info we record should consist of two parts, target_relids and
added_relids.  Vars and PHVs in quals that belong to target_relids
should be adjusted to include added_relids.

Following this idea I come up with attached patch (no comments and test
cases yet).  It fixes the presented case and passes check-world.  Before
finishing it I'd like to know whether this idea works.  Any comments are
appreciated.

Thanks
Richard