Khaled Yagoub

Automatic SQL tuning in oracle 10g

SQL tuning is a very critical aspect of database performance tuning. It is an inherently complex activity requiring a high level of expertise in several domains: query optimization, to improve the execution plan selected by the query optimizer; access design, to identify missing access structures; and SQL design, to restructure and simplify the text of a badly written SQL statement. Furthermore, SQL tuning is a time consuming task due to the large volume and evolving nature of the SQL workload and its underlying data. n nIn this paper we present the new Automatic SQL Tuning feature of Oracle 10g. This technology is implemented as a core enhancement of the Oracle query optimizer and offers a comprehensive solution to the SQL tuning challenges mentioned above. Automatic SQL Tuning introduces the concept of SQL profiling to transparently improve execution plans. It also generates SQL tuning recommendations by performing cost-based access path and SQL structure what-if analyses. n nThis feature is exposed to the user through both graphical and command line interfaces. The Automatic SQL Tuning is an integral part of the Oracles framework for self-managing databases. The superiority of this new technology is demonstrated by comparing the results of Automatic SQL Tuning to manual tuning using a real customer workload.

Self-Tuning for SQL Performance in Oracle Database 11g

Commercial database customers across the board list SQL performance tuning as one of the most time-consuming tasks for database administrators (DBAs). The 10g Oracle Database provides a feature called the SQL Tuning Advisor to simplify the task. The 11g release adds a new database feature, called Automatic SQL Tuning, that closes the feedback loop for the first time, fully automating the SQL tuning workflow and solving some SQL performance problems without any DBA intervention.

Optimizer plan change management: improved stability and performance in Oracle 11g

Execution plans for SQL statements have a significant impact on the overall performance of database systems. New optimizer statistics, configuration parameter changes, software upgrades and hardware resource utilization are among a multitude of factors that may cause the query optimizer to generate new plans. While most of these plan changes are beneficial or benign, a few rogue plans can potentially wreak havoc on system performance or availability, affecting critical and time-sensitive business application needs. The normally desirable ability of a query optimizer to adapt to system changes may sometimes cause it to pick a sub-optimal plan compromising the stability of the system. n nIn this paper, we present the new SQL Plan Management feature in Oracle 11g. It provides a comprehensive solution for managing plan changes to provide stable and optimal performance for a set of SQL statements. Two of its most important goals are preventing sub-optimal plans from being executed while allowing new plans to be used if they are verifiably better than previous plans. This feature is tightly integrated with Oracles query optimizer. n nSQL Plan Management is available to users via both command-line and graphical interfaces. We describe the feature and then, using an industrial-strength application suite, present experimental results that show that SQL Plan Management provides stable and optimal performance for SQL statements with no performance regressions.