Choosing Physical Tuning Options

This section contains the following topics:

Overview

Placement of Entities in Areas

Data Compression

Relationship Tuning Options

Index Key Compression

Non-SQL Tuning Options

Physical Tuning Options for Commonweather Corporation

Overview

Physical tuning options

The following database options can be used to ensure optimal performance in individual business transactions:

Placement of entities in areas—To facilitate certain processing operations, you can instruct CA IDMS/DB to divide the database into separate areas. Each area can contain one or more entities.
You can also sometimes simplify application processing, recovery procedures, and unload/load operations by segmenting the database.
ata compression—To save disk space, you can instruct the database to compress data before it is stored and decompress it when it is retrieved.
Relationships and tuning options—When relating entities, you can establish linked or unlinked relationships. Linked relationships can be used to optimize performance in applications that process related entities.
Index key compression—To save disk space, you can instruct CA IDMS/DB to compress indexes.
Non-SQL tuning options
- Multimember relationships—A single relationship is maintained for multiple child entity types.
- Direct location mode—You can assign this location mode to an entity when the application programmer must be able to explicitly specify the physical location of entity occurrences in the database.
- Variable-length entities—You can collapse two entities involved in a one-to-many relationship where the many entity can contain a variable number of occurrences.
- Database procedures—You can write and compile database procedures to be executed at application runtime when a program accesses an area or entity to perform predefined programming functions such as data compression and decompression.
- CALC duplicates options—You can specify options for nonunique CALC keys specifying how these nonunique occurrences will be stored in the database.
- Relationship tuning options—You can specify options as part of the definition of a relationship to specify the order of child occurrences, how the occurrences will be linked with each other, how new occurrences are introduced into the relationship, and how existing occurrences can be modified.
- Index tuning options—You can specify options as part of the definition of an index to provide for unlinking the index and for determining the order in which entity occurrences will be referenced in the index, how new occurrences are introduced into the index, and how existing occurrences can be modified.

Each of these tuning options is described in detail below.