Re: Wrong result when enable_partitionwise_join is on if collation of PartitionKey and Column is different.

[jian he]

looks good to me.
I didn't find any issue.

group_by_has_partkey can even cope with:
EXPLAIN (COSTS OFF, settings)
SELECT c collate "C" collate case_insensitive collate "C", count(c)
FROM pagg_tab3 GROUP BY c collate "C" collate case_insensitive collate
"C" ORDER BY 1;

so i guess in group_by_has_partkey
                if (IsA(groupexpr, RelabelType))
                    groupexpr = ((RelabelType *) groupexpr)->arg;
should be enough.

not need while loop.

    while (IsA(groupexpr, RelabelType))
        groupexpr = (Expr *) (castNode(RelabelType, groupexpr))->arg;