Query Optimization for Distributed Database Systems
Robert Taylor, Dan Olteanu · 2010
I would like to thank my supervisor Dr Dan Olteanu for his incredible level of enthusiasm and encouragement throughout the project. I am also very grateful for the continuous level of feedback and organisation as well as the amount of time he has devoted to answering my queries. I feel that I now approach complex and unknown problems with enthusiasm instead of apprehension as I used to. I couldn’t The query optimizer is widely considered to be the most important component of a database management system. It is responsible for taking a user query and searching through the entire space of equivalent execution plans for a given user query and returning the execution plan with the lowest cost. This plan can then be passed to the executer, which can carry out the query. Plans can vary significantly in cost therefore it is important for the optimizer to avoid very bad plans. In this thesis we consider queries in positive relational algrebra form involving the conjunction of projections, selections and joins. The query optimization problem faced by everyday query optimizers gets more and