Re: JumbleQuery ma treat different GROUP BY expr as the same

hi.

while working on it, I guess I found another bug, below JumbleQuery will return
the same result:

SELECT FROM (VALUES (1::INT, 2::INT)) AS t(a, b) ORDER BY a, b;
SELECT a FROM (VALUES (1::INT, 2::INT)) AS t(a, b) ORDER BY a, b;
SELECT a, b FROM (VALUES (1::INT, 2::INT)) AS t(a, b) ORDER BY a, b;

so I think TargetEntry.resjunk should not be marked as query_jumble_ignore.

addRangeTableEntryForGroup
will make RangeTblEntry(RTE_GROUP) have a newly copied original groupexprs.
Query->targetList also has the original groupexprs.

but after parseCheckAggregates->substitute_grouped_columns.
Query->targetList Var node will point to the offset of the RTE_GROUP,
not the RTE_RELATION.
see src/backend/parser/parse_agg.c line 1543.

After parseCheckAggregates, JumbleQuery(Query->targetList) will produce the same
result as long as the grouping columns have the same list of data types.
JumbleQuery(Query->groupClause) will also produce the same result
as long as the grouping columns have the same list of data types.

Since only the RangeTblEntry(RTE_GROUP) have the original grouping expressions,
we can not mark the RangeTblEntry->groupexprs as query_jumble_ignore.

looking at, transformUpdateTargetList->transformTargetList
so i think it's OK to remove query_jumble_ignore from TargetEntry.resjunk for
INSERT/UPDATE/DELETE.

--
jian
https://www.enterprisedb.com/