Choosing a Cursor Type

Because there are many ways for a cursor to interact with the result set and your application, there are many types of cursors that your application can use. As a general rule, your application should use the simplest cursor that provides the required data access. Each additional cursor characteristic beyond the basics (static, read-only, forward-only, scrolling, unbuffered) has a price — either in client memory, network load, or performance. In many cases, the default cursor options generate a far more complex cursor than your application actually needs.

Your cursor type choice depends on how your application uses the result set and on several design considerations, including the size of the result set, the percentage of the data likely to be used, sensitivity to data changes, and application performance requirements.

At its most basic, your cursor choice depends on whether you need to change or simply view the data:

• If you just need to scroll through a set of results, but not change data, use a forward-only or static cursor.
• If you have a large result set and need to select just a few rows, use a keyset cursor.
• If you want to synchronize a result set with recent adds, changes, and deletes by all concurrent users, use a dynamic cursor.

Although each cursor type seems to be distinct, keep in mind that these cursor types are not so much different varieties as simply the result of overlapping characteristics and options.

Information in the following topics will acquaint you with the available cursor types.