Summary of Research...
Se Ar Ch, Prasan Roy · 2007
rk I have been working on multi-query optimization and its applications, and on online garbage collection algorithms for object oriented databases. Multi-Query Optimization: We consider the problem of query optimization where either a single query has repeated subexpressions or multiple queries have common subexpressions. This problem is known as multi-query optimization, and is of importance because of the increasing use of complex decision support queries on large sets of data, particularly in data warehouses. Such queries typically benefit a lot from elimination of redundancies due to recomputation of repeated and shared subexpressions. Traditional query optimizers are not appropriate for optimizing queries with common subexpressions, since they make locally optimal choices, and may miss globally optimal plans. We propose several novel and practical cost-based algorithms for multi-query optimization, based on the compact AND-OR DAG representation of querie