Defining Physical Databases › Overview › Segments

Segments

Represent a Physical Database

A segment represents a physical database usually defined by a single schema. It describes the collection of areas and files containing the data of the database. One logical definition (schema) can be associated with one or more physical definitions (segments). Each of these segments contains areas and files.

Areas Define Range of Database Pages

An area is a logical file divided into database pages. A database page represents a logical file block.

Database Pages Physically Stored in Files

You assign an area's pages to one or more physical disk files that exist on direct access volumes. At runtime, CA IDMS/DB maps a page in an area to one or more blocks in a file; the way CA IDMS/DB maps a database page to a physical file depends on the file's access method.