Physical Modeling › Indexes

Indexes

An index is a special type of object designator that is used in relational databases to speed up data retrieval. Just as an index in a book helps you to quickly find information by listing all the pages where a particular topic is discussed, an index in a database table points to all the rows where a particular column value is stored. You can use indexes in two ways:

• To sequentially access the indexed file.
• To directly access individual records in the indexed file based on a given value for the indexed field.

The following types of indexes are supported:

• Primary Key (PK) index
• Foreign Key (IF) index
• Alternate Key (AK) indexes
• Inversion Entry (IE) indexes

You can create indexes in your model. An index is a component of your model that you manage at the physical level. However, at the logical level, you can define key groups that transform into alternate key and inversion entry indexes at the physical level.

When you forward-engineer your model to generate a database schema, a separate index is automatically created on the primary key of each table, as well as on all alternate keys, foreign keys, and inversion entries, since these columns are most frequently used to search for data. You can use any of the automatically generated indexes to easily create indexes as your business requirements change. When you create an index, you can assign different columns to it, and you can change the index properties of your particular database applications.

More information:

Alternate Key Indexes

Create a Unique or Non-Unique Index

Define Index Members

Display an Index Only in the Physical Model

Enter an Index Comment

Enter Index User-Defined Property Values

Index Default Values

Table Index Editor

Inversion Entry Indexes

Reorder Index Members

Prevent an Index From Generating in the Schema

Primary Key Indexes