books.google.com - Tuning of SQL code is generally cheaper than changing the data model. Physical and configuration tuning involves a search for bottlenecks that often points to SQL code or data model issues. Building an appropriate data model and writing properly performing SQL code can give 100%+ performance improvement....http://books.google.com/books/about/Oracle_Performance_Tuning_for_10gR2.html?id=wgBMWCvTEHQC&utm_source=gb-gplus-shareOracle Performance Tuning for 10gR2
