Space Management

Definitions of Areas and Pages

A CA IDMS database contains one or more areas. Each database area is a named subdivision of addressable storage in the database. A CA IDMS area is subdivided into database pages. Most database pages are used to hold actual record occurrences (or rows). Some pages are reserved by CA IDMS for space management.

Note: Record occurrences and rows of an SQL-defined table are stored in the same way in a CA IDMS database. For simplification, the term record occurrence will be used to indicate both row and record occurrence, and record type to indicate both table and record type.

Definition of Database Key

Each record occurrence in a CA IDMS database is uniquely identified by a database key (db-key) that specifies the physical location of the occurrence. Database keys are used as pointers to related record occurrences or index records.

The format of a database key can vary from database to database. The variable format of the db-key allows you to tailor space management factors to different processing requirements.