Database query optimization method that provides for selective restriction of an operation. A query plan for a query is received. The query plan includes an operation to be executed on a table. The received query plan is traversed to determine at least one table in the query plan having a mapping with a threshold rule and based upon a determination that there is at least one table in the query plan having a mapping with the threshold rule, substituting the operation on the at least one table identified in the query plan to another operation having the mapping with the threshold rule.