On Tue, May 30, 2023 at 10:28 AM Richard Guo <guofengli...@gmail.com> wrote:

> I haven't thought through how to fix it, but I suspect that we may need
> to do more checking before we decide to remove PHVs in
> remove_rel_from_query.
>

Hmm, maybe we can additionally check if the PHV needs to be evaluated
above the join.  If so it cannot be removed.

--- a/src/backend/optimizer/plan/analyzejoins.c
+++ b/src/backend/optimizer/plan/analyzejoins.c
@@ -425,7 +425,8 @@ remove_rel_from_query(PlannerInfo *root, int relid,
SpecialJoinInfo *sjinfo)

        Assert(!bms_is_member(relid, phinfo->ph_lateral));
        if (bms_is_subset(phinfo->ph_needed, joinrelids) &&
-           bms_is_member(relid, phinfo->ph_eval_at))
+           bms_is_member(relid, phinfo->ph_eval_at) &&
+           !bms_is_member(ojrelid, phinfo->ph_eval_at))
        {
            root->placeholder_list =
foreach_delete_current(root->placeholder_list,
                                                            l);

Does this make sense?

Thanks
Richard

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