Visual Analysis of Cost Based Database Optimizers Using Picasso Tool

Cost based query optimizers have seen numerous changes and up gradations since their birth in the form of System R query optimizer. Query Optimization is a process of selecting an optimal Query Execution Plan from a number of plans available for execution of query and this selection of best plan is very critical to the performance of a relational database. Picasso is a Query Optimizer analysis tool developed by the Database lab of Indian Institute of Science, Bangalore [24]. It provides graphical insights into the Query Optimization Process. With so many Database systems available in the market and each one having its own secret recipe of Query Optimization it becomes difficult to know what actually happens during query optimization. Picasso enables users to explore the world of query optimization. In this paper we briefly introduce the query optimization concept and then describe a special technique known as Plan Diagram Reduction which improves the efficiency of Query Optimization Process and makes it more Robust.