The data callback classes can be used with Oracle to insert and fetch data. These classes are useful for very large data that may not fit in memory for a single database call and are described in Section 15.3, “The Data Callback Classes,” in the DB Interface Module User’s Guide.

Oracle supports sending multiple rows of data for one execution of an insert statement. Retrieving multiple rows of data on each call to RWDBOSql::fetch() is also supported.

The DB Access Module for Oracle sets the piece size for inserting or fetching data to 32768. This value represents bytes in the case of binary data, and code units in the case of character data.

The piece size setting can be accessed and modified with the method RWDBOCISystemHandle::piecewiseSize(). Please refer to the class reference description for RWDBOCISystemHandle for more information.

When inserting data using data callbacks, Oracle does not require the length of the data being inserted. Therefore, the method RWDBDataCallback::getLength() does not need to be overridden in derived classes.

Stored procedure execution is not supported with the data callback classes.