Plan Stability: What Are the Pitfalls and Is It What You Think It Is?
Database administrators sometimes need to control or change SQL execution plans. If application code can be modified, then DBAs or database architects might ask application developers to make SQL statement changes or apply query hints. Alternatively, the DBA might change the physical database design or use SQL management objects (such as SQL profiles and SQL plan baselines) and avoid any need for change in the application. Allied to this, some application developers routinely hint SQL statements in an attempt to mitigate any need for SQL tuning later on.
There are many approaches to plan stability, and the Oracle Database provides a wide variety of solutions. But what are the pitfalls of each approach and what can the DBA do in mitigation? What does a good approach look like? Behind all of this there is often a desire to fix SQL execution plans to prevent them ever changing. Is this an advisable thing to do? If not, then what is the alternative?
This session covers the different approaches to plan stability, and helps you to understand which techniques are at your disposal and how they are best applied.