User`s guide

Creating indexes for database tables can increase the speed of data access and reduce the time it
takes for the program to evaluate data. Some DBMS applications automatically index your database
tables, while others require that you create an index yourself. For the best report generation performance,
make sure each of your database tables has a corresponding index.
Note:
Some DBMS applications do not support indexed tables. Refer to the documentation for your DBMS
to find out if it supports indexes and how to create them. If your DBMS documentation does not mention
indexed tables, it may not support them, and you should link tables based on common fields. The Links
tab of the Database Expert can also help you determine if your tables include indexes.
Indexes organize the records in a relational database table so that data can be located easier. For
example, assume you have a table with the following data:
AmountCustomerOrder#
25141.50Allez Distribution10444
19164.30BG Mountain Inc.10470
8233.50Sierra Mountain10485
24580.50Mountain Toad10488
7911.80SFB Inc.10495
1956.20La Bomba de Bicicleta10501
1683.60BG Mountain Inc.10511
19766.20Sierra Bicycle Group10544
29759.55Mountain Tops Inc.10568
12763.95Sierra Bicycle Group10579
The information in this table is organized according to the Order# field. This is fine anytime you want
to look up information in the table based on order numbers. However, what if you want to look up
information specific to a certain customer?
Say you want to look up all orders made by Sierra Bicycle Group. The database engine must begin by
looking at the first order number in the list and checking to see if the customer name matches the
2012-03-14505
Understanding Databases