A method, computer system and computer program product, the method comprising: upon receiving a database query comprising at least a first and a second join operations: storing the database query in the memory; identifying by the processor within the database query the first join operation, wherein the first join operation is a many-to-many join operation or a one-to-many join operation between a first table and a second table, in which fields of the second table are used only for filtering rows from the first table or for joining with another table; and converting by the processor the first join operation to an enhanced operation which eliminates returning at least two matches for at least one row from the first table when the database query is executed.