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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
Data type size
A fixed-length opaque data type

A fixed-length opaque data type

When you specify the actual size for INTERNALLENGTH, you create a fixed-length opaque data type. The size of a fixed-length opaque data type must match the value that the C-language sizeof() directive returns for the internal structure. The maximum internal length for a fixed-length opaque type is 32760 bytes.

On most compilers, the sizeof() directive rounds up to the nearest 4-byte size to ensure that pointer match on arrays of structures works correctly. However, you do not need to round up for the size of a fixed-length opaque data type. Instead you can specify alignment for the opaque data type with the ALIGNMENT modifier. For more information, see Memory alignment.