tailieunhanh - Oracle Database Administration for Microsoft SQL Server DBAs part 26

Oracle Database Administration for Microsoft SQL Server DBAs part 26 takes the administration topics with which the SQL Server DBA is familiar, translates them into Oracle terms, and then expands on Oracle functionality. Definitions and comparative terms run throughout the book so the SQL Server DBA can easily leverage existing knowledge. This Oracle Press guide also expands on some of the features in Oracle that do not match up directly with SQL Server, and looks at other processes often performed on an Oracle database that would not typically be a standard practice in SQL Server environments | 232 Oracle Database Administration for Microsoft SQL Server DBAs ORACLE Enterprise Manager 11g Database Control Database Instance IMOtVl Database togged n as SYS Iniliulizuliun PuTcM titters Cirrent bKHle__ U irr Basic Mxlirted Dynamic Category 1 All v All v All v Optimizer Go T1 Apply changes n current rumrg nstance s mode to SH-ile. f-cr static parameters you must restart Te database. aaretoiiie j FIGURE 8-5. Optimizer parameters Depending on the type of database that is running several of these parameters may be useful for tuning including the following The STAR_TRANSFORMATION_ENABLED parameter would probably be set to true if the database has more of a data warehousing purpose rather than is just used as a transactional database. The OPTIMIZER_INDEX_COST_ADJ parameter can be adjusted to make the optimizer more willing to use indexes. The setting is a percentage to adjust the cost of using indexes in the query plans. For example reducing the value of this parameter from 100 to 50 would cut the cost of using an index in half. The OPTIMIZER_MODE parameter chooses the approach for the database instance. first_rows will find a best plan to return the first set of rows faster. all_rows will develop the plan to return all of the values of the query in the session. Chapter 8 Performance and Tuning 233 Adjusting the parameters can help change how the optimizer behaves and can also give the database instance more resources especially when increasing the memory parameters to allocate more memory to the system. Some of the default settings might be valid for simple database environments. The type of database environment and how it is being used in general should be considered when adjusting these parameters. Additional information from the snapshot reports and advisors that run in the database can help determine the appropriate settings and configurations for some of the parameters. Automatic Workload Repository The Automatic Workload Repository AWR contains .

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