What are the General Transformation Rules for Relational operations?
Ans: The transformation rules transform one relational algebra expression to AN
EQUIVALENT ONE
1. Employed by the query optimizer to optimize query tree
2. Any type of rule, if applied, ensures that the resultant tree is equivalent → resulting execution plan is equivalent
General Transformation Rules is as follow:
1. Commutativity of s: The s operation is commutative:
- sc1 (sc2(R)) = sc2 (sc1(R))
- More selective selections first