There are three parts to tuning an Oracle database: data modeling, SQL code tuning and physical database configuration.  A data model contains tables and relationships between tables. Tuning a data model involves normalization and de-normalization. Different approaches are required depending on the application, such as OLTP or a Data Warehouse. Inappropriate database design can make SQL code impossible to tune. Poor data modeling can have a most profound effect on database performance since all SQL code is constructed from the data model.   Poorly written SQL code is often a culprit of performance problems and is expensive to rectify. However, tuning of SQL code is generally cheaper than changing the data model. SQL code tends to be contained inside independent blocks within applications or stored procedures.  Physical database tuning involves hardware resource usage, networking and various other Oracle things such as configuration and file distribution. Physical configuration is often a culprit of poor performance where Oracle is installed with defaults, and never altered by an expert.                                         *Includes all three aspects of Oracle database tuning: data model tuning, SQL & PL/SQL code tuning, physical plus configuration tuning *Contains experienced guidance and real-world examples using large datasets                                              *Emphasizes development as opposed to operating system perspective

Oracle High Performance Tuning for 9i and 10g PDF

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