Hmmm.... the subselect is invalid, but not rejected. The outer select returns every row in the customer_order_matches table. This seems pretty wrong. This is PG 9.2.1 running on Ubuntu.
db=> select count(1) from customer_order_matches where customer_order_item_id in (select customer_order_item_id from customer_order where customer_order_id = 105862140); count ------- 36180 (1 row) db=> select customer_order_item_id from customer_order where customer_order_id = 105862140; ERROR: column "customer_order_item_id" does not exist LINE 1: select customer_order_item_id from customer_order where cust... ^ Craig