All database systems could implement many more optimizations. Heck, all these tricks to get the queries to complete faster are only needed because the database

All database systems could implement many more optimizations. Heck, all these tricks to get the queries to complete faster are only needed because the database engine did not find this fast execution plan. The problem is the more optimizations you implement the more possibilities the query planner has to evalue which may result in (1) a too long query planning phase or (2) the possibility of de-optimizing a good query because an optimization was falsely predicted to be faster