LOBs in External Procedures

LOB locators can be passed as arguments to an external procedure. The corresponding C routine gets an argument of type OCILobLocator *. For example, a PL/SQL external procedure could be defined as:

FUNCTION DS_Findmin(data CLOB) RETURN PLS_INTEGER IS EXTERNAL 
                   NAME "c_findmin" LIBRARY DS_Lib LANGUAGE C;

When this function is called, it invokes a routine (c_findmin) with the signature:

int   c_findmin (OCILobLocator *)

This routine in a shared library associated with DS_Lib. In order to use the pointer OCILobLocator * to get data from the LOB (for example, using OCILobRead()), you must reconnect to the database by performing a callback. External procedures and callbacks are discussed in "Doing Callbacks".