The PRIORITY parameter takes effect when more records target to a page than that page can hold. When this happens, the priorities you assigned to record types are used to determine which records (or group of record types) are stored on the target page and which ones should overflow if the page is full.
The sublist feature of the PRIORITY parameter allows you to specify that two or more record types have the same priority, and it allows you to specify that VIA members and their non-VIA owner are to be stored in a cluster. However, if the owner location mode is VIA, then all the owner records are clustered together followed by their member records. In the example at the bottom of the previous figure, the type B records are clustered near their type A owners.
When you rank record types using the PRIORITY parameter, CA IDMS/DB Reorg accommodates your priority requests by altering its allocation techniques as needed. CA IDMS/DB Reorg's default priority order is DIRECT, CALC, and VIA.
You can rank individual records or groups of record types. For example, if you specify a sublist of record types as first priority, and DIRECT records as second priority, you are overriding CA IDMS/DB Reorg's automatic record allocation techniques. By using the PRIORITY parameter you can tailor the physical structure of the database to meet your needs, based on your processing requirements.
|
Copyright © 2014 CA.
All rights reserved.
|
|