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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.
DataBlade® Developers KitThe DataBlade® Developers Kit (DBDK) guides contain information about the tools you can use to develop and package DataBlade® modules, which extend the functionality of HCL OneDB™ databases.
DataBlade® Developers Kit User's GuideThe HCL OneDB™ DataBlade® Developers Kit Users Guide describes how to use OneDB® DataBlade® Developers Kit (DBDK) tools to develop and package DataBlade® modules.
Create DataBlade® objects by using BladeSmithUse BladeSmith to create DataBlade® modules.
Create DataBlade® module objectsBladeSmith uses wizards to create and edit objects.
Create castsA cast is a conversion from one data type to another. The cast accepts the source data type as its argument and returns the target data type.
Implicit and explicit casts

Implicit and explicit casts

You can specify whether a cast is called for implicit conversions. Implicit conversions allow the database server to use the cast when it is not called explicitly in an SQL statement.

For example, if you call the Plus() function with a DOLLAR argument, the database server searches for an implicit cast from DOLLAR to a data type for which the Plus() function is defined. If an implicit cast exists, the database server calls the conversion function and then calls the Plus() function without error. If no cast is specified with implicit conversion, the Plus() function call results in an error message from the database server.

In this example, you create an implicit cast from DOLLAR to DOUBLE PRECISION to permit the database server to execute all functions defined for DOUBLE PRECISION on DOLLAR values. However, if you define a cast from DOLLAR to INTEGER, you do not want that cast to be implicit, because the conversion function truncates dollar values, resulting in inaccurate results.