On Fri, May 24, 2024 at 9:08 PM Richard Guo <guofengli...@gmail.com> wrote: > On the basis of the parser infrastructure fixup, 0002 patch adds the > nullingrel bit that references the grouping RTE to the grouping > expressions.
I found a bug in the v6 patch. The following query would trigger the Assert in make_restrictinfo that the given subexpression should not be an AND clause. select max(a) from t group by a > b and a = b having a > b and a = b; This is because the expression 'a > b and a = b' in the HAVING clause is replaced by a Var that references the GROUP RTE. When we preprocess the columns of the GROUP RTE, we do not know whether the grouped expression is a havingQual or not, so we do not perform make_ands_implicit for it. As a result, after we replace the group Var in the HAVING clause with the underlying grouping expression, we will have a havingQual that is an AND clause. As we know, in the planner we need to first preprocess all the columns of the GROUP RTE. We also need to replace any Vars in the targetlist and HAVING clause that reference the GROUP RTE with the underlying grouping expressions. To fix the mentioned issue, I choose the perform this replacement before we preprocess the targetlist and havingQual, so that the make_ands_implicit would be performed when we preprocess the havingQual. One problem with this is, when we preprocess the targetlist and havingQual, we would see already-planned tree, which is generated by the preprocessing work for the grouping expressions and then substituted for the GROUP Vars in the targetlist and havingQual. This would break the Assert 'Assert(!IsA(node, SubPlan))' in flatten_join_alias_vars_mutator and process_sublinks_mutator. I think we can just return the already-planned tree unchanged when we see it in the preprocessing process. Hence here is the v7 patchset. I've also added detailed commit messages for the two patches. Thanks Richard
v7-0001-Introduce-a-RTE-for-the-grouping-step.patch
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v7-0002-Mark-expressions-nullable-by-grouping-sets.patch
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