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120 | Chapter 4: Oracle Data Structures
You can also view the execution plan through Enterprise Manager for the SQL statements
that use the most resources. Tuning your SQL statements isn??™t a trivial task,
but with the EXPLAIN PLAN and TKPROF utilities you can get to the bottom of the
decisions made by the cost-based optimizer. It takes a bit of work to understand
exactly how to read an execution plan, but it??™s better to have access to this type of
information than not. In large-scale system-development projects, it??™s quite common
for developers to submit EXPLAIN PLANs for the SQL they??™re writing to a DBA as a
formal step toward completing a form or report. While time-consuming, this is the
best way to ensure that your SQL is tuned before going into production.
SQL Advisors
Oracle Database 10g added a tool called the SQL Tuning Advisor. This tool performs
advanced optimization analysis on selected SQL statements, using workloads
that have been automatically collected into the Automatic Workload Repository or
that you have specified yourself.


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