Disabling a default function mapping

Default function mappings cannot be dropped. However, you can render them inoperable by disabling them.

Before you begin

The privileges held by the authorization ID of the statement must have SYSADM or DBADM authority.

Procedure

To disable a default function mapping, the CREATE FUNCTION MAPPING statement specifies the name of the database function and sets the DISABLE option to 'Y'.

Example: Disable a default function mapping between the database SIN function and a similar function on Oracle data sources

When a query that requests Oracle data and that references SIN is processed, either function might be invoked. The function invoked depends on which function is estimated by the query optimizer to require less overhead.

To ensure that the database SIN function is invoked and that the Oracle SIN function is not invoked, you must disable the default function mapping. Use the following syntax:

CREATE FUNCTION MAPPING FOR SYSFUN.SIN(INT)  
TYPE ORACLE OPTIONS (DISABLE 'Y')