consider the window function: ```sql substr( ref_1.cp_type, sum(CASE WHEN ref_1.cp_type = 0 THEN 3 ELSE 2 END) OVER (), 1) ``` Before the pr, only "CASE WHEN ref_1.cp_type = 0 THEN 3 ELSE 2 END" is pushed down. But both "ref_1.cp_type" and "CASE WHEN ref_1.cp_type = 0 THEN 3 ELSE 2 END" should be pushed down. This pr fix it