Opaque Data Type Support Routines

The routines you can specify for opaque data types in the Opaque Type wizard fall into the following categories:

• Internal support routines for data types

These routines are automatically called by the database server when processing the data types; they cannot be called from SQL.

This category includes text input and output functions, binary send and receive functions, text file import and export functions, binary file import and export functions, and the Assign() function and Destroy() procedure.

• Data type comparison functions

The Equal() and NotEqual() operator functions call the Compare() internal support function to compare two opaque data types when called from SQL: for example, to support an ORDER BY clause.

• B-tree and R-tree access method support and strategy functions

Access method support functions are called by the server when processing secondary indexes. Access method strategy functions are called by the user in SQL; they signal the database server to use the associated access method to retrieve the result of the query.

The B-tree support function is Compare(). The B-tree strategy functions are Equal(), LessThan(), GreaterThan(), LessThanOrEqual(), GreaterThanOrEqual(); they are all bound to operators.

The R-tree support functions are Union(), Size(), and Inter(). The R-tree strategy functions are Equal(), Overlap(), Contains(), and Within().

• Overloaded built-in functions

Overloaded mathematical functions take one or two opaque data types, perform the mathematical operation, and return the resulting opaque data type. The mathematical functions are Plus(), Minus(), Times(), Divide(), Positive(), and Negate().

The overloaded Concat() function concatenates two opaque data types. The overloaded Hash() function supports hashing for an opaque data type.

For more information, see the DataBlade Developers Kit User's Guide.