Major Description
We will pull out complex join keys from grouping expressions, so the project can hold a alias with expression. Unfortunately we may lose the output partitioning since the current AliasAwareOutputExpression only support preserve the alias with attribute.
For example, the follow query will introduce three exchanges instead of two.
SELECT c1 + 1, count(*) FROM t1 JOIN t2 ON c1 + 1 = c2 GROUP BY c1 + 1
