"Normal" readmulti operations return a set of database records as an ArrayList. There are several situations in which you might want to replace this type of standard "normal" readmulti operation with your own specialized processing.
An example is in batch processing where you want to iterate across a large number of records on a database table, and process each record in turn. It is not feasible to use a standard readmulti operation to assemble an in-memory vector of all of the records read before processing. Another common example is where you want to lock or delete records from the result set as they are processed. In each of these examples you can write your own readmulti operations to process records individually as they are retrieved from the database rather than relying on the standard processing supplied by StandardReadMultiOperation.