(last updated June 15, 1998)
CHOP: Optimization of a Batch of Schema Evolution Operations
A schema evolution operation thus far is executed as one single atomic task, possibly requiring to access all objects in the to-be-modified class or even class hierarchy. Optimization has been proposed in the context of commercial DBMS systems, namely the O2 system, to apply deferred evolution - by only modifying objects if and when accessed for retrieval purposes. Our system sometimes executes complete sequences of schema evolution operations. Our goal has been to optimize such batches by first reordering them subject to data dependency constraints, then by either merging, cancelling or eliminating operations in the sequence, whenever possible. We will first design optimization strategies, then implement them on PSE, and lastly run performance studies to evaluate the proposed approach.