Oracle PL/SQL for DBAs

Using Cursors for More Than Queries

As the Oracle database has evolved over time, so has the humble cursor. In addition to providing the performance improvements described in earlier sections, cursor functionality now extends beyond queries, and it is integral to the design and building of applications. This section describes a variety of additional cursor capabilities not explored in previous sections.

Bulk fetching, REF cursors, cursor parameters, and cursor expressions are especially handy tools for DBAs who need ways to investigate and improve the performance of applications. The features discussed here are particularly helpful if you are working with very busy databases where keeping the number of records touched to an absolute minimum is very important. For example, REF cursors can be used to control data access from client applications that may not even be aware of the way that tables are structured. Cursor parameters allow data access to be spread out. (Chapter 3 discusses additional tools for accomplishing this goal.) And cursor expressions (nested cursors) go a long way toward ensuring that only the work that needs to be done actually is done.