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Evaluating Query and Transaction Performance

Performance tuning is an iterative process. Each query and each database server is different, so you must use your judgement to evaluate the output of tuning utility programs and make tuning decisions. After you make tuning adjustments, re-evaluate the effect and make further adjustments if necessary.

This section describes a general approach to evaluating a particular query or transaction. The information comes from user experience.

Tip:
Before you begin to evaluate queries and transactions, create a text file or printout that maps all of the coservers and disks on the database server. The file should contain all disk aliases, so that you can easily compare statistics that the operating system produces as well as output from the database server utilities. For quick reference when you are evaluating command-line utility output, you might also create a file that contains the names of all tables and the dbspaces or dbslices across which they are fragmented.

Note:
The Cartesian Product alarm is triggered when a Cartesian product is used in a query. This alarm is enabled only if a server-wide environment variable is set.

After you analyze the context of the query or transaction and its specific requirements, you can decide how to adjust it for better performance.

The following sections contain general advice about such adjustments. For detailed suggestions, see Appendix C. Application Tuning Examples.

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