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Extending HCL OneDB™Beyond standard relational database objects, HCL OneDB™ can be extended to handle specialized data types, access methods, routines, and other objects. HCL OneDB™ includes many built-in extensions that are fully integrated in the database server. HCL OneDB™ also provides DataBlade® modules, which are packages of extended database objects for a particular purpose and that are installed separately from the database server. Alternatively, you can create your own user-defined objects for HCL OneDB™.
Creating extensionsYou can create user-defined data types, routines, access methods, and other database objects to suit your needs. You can use application programming interfaces to write user-defined routines and applications that access data in HCL OneDB™ databases.
User-Defined Routines and Data Types Developer's GuideThe HCL OneDB™ User-Defined Routines and Data Types Developer's Guide describes how to define new data types and enable user-defined routines (UDRs) to extend HCL OneDB™.
Create an opaque data type
Creating an opaque data type
Create the internal structure in C
Parameter passing

Parameter passing

The database server can pass opaque-type values to a UDR in either of the following ways:

Pass by value passes the actual value of the opaque data type to a UDR.
Pass by reference passes a pointer to the value of the opaque data type to a UDR.

By default, the database server passes all opaque types by reference. For the database server to pass an opaque data type by value, specify the PASSEDBYVALUE modifier in the CREATE OPAQUE TYPE statement. Only an opaque data type whose size is 4 bytes or smaller can be passed by value. However, the DataBlade® API data type mi_real, although only 4 bytes in length, is always passed by reference.

The following CREATE OPAQUE TYPE statement specifies that the two_bytes opaque data type be passed by value:

CREATE OPAQUE TYPE two_bytes (INTERNALLENGTH=2, ALIGNMENT=2,
   PASSEDBYVALUE);