Yeah, I can reproduce $subject on HEAD.
But I found this when debug into group_by_has_partkey(), as below:
call nodeToString(groupexprs):
VAR : varcollid 16384
call nodeToString(partexpr):
VAR: varcollid 16384
So the collid of partkey and groupexpr is same, so add check here may not fix this issue.
I continue to find out why the collation id of partkey is 16384(e.g. case_insensitive). The partkey expr info is
set in set_baserel_partition_key_exprs(), which it uses partkey->parttypcoll[cnt] value not partkey->partcollation value.
And partkey->parttypcoll[cnt] is assigned from pg_attribute , which is the column c meta data.
Should we use partkey->partcollation value? I try to fix that in the attached patch. I add your case in the test, and I don't find
failed regress.
