Query Optimization For over three decades, Oracle's Database technology has led the industry in performance and scalability. Oracle Database 11 g builds on a powerful array of query optimization features that maximize performance and allow DBAs to become more productive by providing innovation in plan stability. Read on to know more about the latest Oracle Database query optimizations.
How Do I know what Extended Statistics I need to create?
Extended statistics, help the Optimizer improve the accuracy of cardinality estimates for SQL statements that contain predicates involving a function wrapped column (e.g. UPPER(LastName)) or multiple columns from the same table used in filter predicates, join conditions, or group-by keys. So extended statistics are extremely useful but how do you know which extended statistics should be created? In Oracle Database 18.104.22.168 we introduced Auto Column Group Creation, which automatically determines which column groups are required for a table based on a given workload. Please note this functionality does not create extended statistics for function wrapped columns it is only for column groups. More information on how Auto Column Group Creation works can be found here.