Application Development Guide

Scalar Function Error Processing

The error processing model for scalar UDFs which are defined with the FINAL CALL specification is as follows:

• If FIRST call fails, no further calls are made.
• If FIRST call succeeds, then further NORMAL calls are made as warranted by the processing of the statement, and a FINAL call is always made.
• If NORMAL call fails, no further NORMAL calls are made, but the FINAL call is made (if you have specified FINAL CALL).

This means that if an error is returned on a FIRST call, the UDF must clean up before returning, because no FINAL call will be made.

The error processing model for table functions is defined in Table Function Considerations section of this chapter.

Note:

This model describes the ordinary error processing for scalar UDFs. In the event of a system failure or communication problem, a call indicated by the error processing model may not be made. For example, for a FENCED UDF, if the db2udf fenced process is somehow prematurely terminated, DB2 cannot make the indicated calls.