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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™.
Improve UDR performance
Optimize functions in SQL statements

Optimize functions in SQL statements

The optimizer by itself cannot evaluate the cost of executing a function in an SQL statement because of the possibility of complex logic, user-defined types, and so on. Because some functions can be expensive to execute, the creator of the function should provide information about the cost and selectivity of the function to help in optimizing the SQL statement.

For example, the following SQL statement includes two functions:

SELECT * FROM T WHERE expensive(t1) and cheap(t2);

If the cheap() function is less expensive to execute than the expensive() function, the optimizer should place the cheap() function first in the execution plan.

The UDRs discussed in the following topics appear in the WHERE or HAVING clause of an SQL statement. These UDRs return a value of TRUE or FALSE.