The inverse functions sample consists of two projects.
Inverse Function Sample Projects
Project
Description
InverseFnHowTo
The inverse functions sample dataspace, including the top-level data service, a relational physical data service, physical data services corresponding to Java transformation functions, and utility data services.
JavaFunctionLib
A Java project that defines the functions used for transforming the da
Inverse Function Projects
Exploring the Projects
This section describes the principal entities within the two projects that comprise the inverse functions sample.
Exploring the InverseFnHowTo Dataspace Project
The following table describes the data services defined in the InverseFnHowTo dataspace project:
Data Service
Description
Employee
The top-level data service for the project. Examining the query plans for the read methods in the data service shows that predicates are pushed despite data transformations because of inverse functions.
EMP2
The physical data service that accesses the data in the underlying relational database.
DeptFunc
EmpIdFuncs
NameFuncs
The physical data services corresponding to the Java transformation functions in the JavaFuncLib project.
EMP2Util
Contains functions useful for manipulating and fixing the sample data through the test view.
Exploring the JavaFunctionLib Project
The following table describes the data services defined in the JavaFunctionLib project:
Class
Method
Description
DeptLib
deptname()
Converts a department number to a department name.
deptno()
Converts a department name to a department number.
EmpIdLib
empid()
Converts an employee number to a string of the following format: EMPid_number.
empnum()
Converts a string of format EMPid_number to an employee id.
NameLib
firstname()
Extracts the first name from a string (containing a person's full name).
lastname()
Extracts the last name from a string (containing a person's full name).
fullname()
Concatenates the first and last name to form a full name.
Using Inverse Functions to Improve Query Performance
