Scope The book provides comprehensive coverage of database performance tuning and opti- zation using Oracle 8i as the RDBMS. The chapters contain both theoretical discussions dealing with principles and methodology as well as actual SQL scripts to implement the methodology. The book combines theory with practice so as to make it useful for DBAs and developers irrespective of whether they use Oracle 8i. Readers who do not use Oracle 8i can implement the principles via scripts of their own written for the particular RDBMS they use. I have tested each script for accuracy and have included the sample outputs generated from them. An operational database has three levels: conceptual, internal, and external. The c- ceptual level results from data modeling and logical database design. When it is imp- mented via an RDBMS such as Oracle, it is mapped onto the internal level. Database - jects of the conceptual level are associated with their physical counterparts in the internal level. An external level results from a query against the database and, as such, provides a window to the database. There are many external levels for a single conceptual level.