Release 10.1A: OpenEdge Reporting:
Query/Results for Windows

> ## Indexes

> The last component of a database is called an index. When you open the drawer of a filing cabinet and thumb through the tabs on the folders, you are using a kind of index. What is on the paper tab represents the information found in the folder. For example, you expect the tabs in the Customer filing cabinet to contain the name of the customer whose information is in that folder. Similarly, an electronic index is a component defined for a specific database table that serves as the basis for faster searching, sorting, or otherwise processing the records in that table.

> In a database, an index is a list that contains a value for each record in the table. When you create an index, you choose the fields used to derive the index value for each record. For example, if you choose the Name field as an index, Progress creates an index for the Customer table that consists of a list of customer names, just like the list of tabs in the paper filing system.

> A simple index is based on the value of one field, while a compound index is based on two or more fields. Figure 1–5 shows an example of a simple and a compound index.

> Figure 1–5: Simple and compound indexes

Copyright © 2005 Progress Software Corporation www.progress.com Voice: (781) 280-4000 Fax: (781) 280-4095