Database Concepts › Physical Structures › Location Mode

Location Mode

Location mode is the user-specified method that determines where record occurrences are stored within an area. The following methods are available:

• CALC- A record is stored on or near a page calculated by the database engine (DBMS) using the value of the element(s) comprising the CALC key.
• VIA (Clustering)- A set member record is stored on or near the page containing its owner record occurrence. If the owner and member are assigned to different areas, the member record is stored at the same relative position in its area as the owner record is in its area.
• DIRECT- A record is stored on or near a user-specified page.

The location mode is used to determine the target page for a new record. The new occurrence is placed on the target page if there is sufficient space. If not, DBMS places it on the next page in the area that has sufficient space. If the end of the area is reached without locating a page, the DBMS searches from the beginning of the area for the first page with sufficient space available. If a record cannot be placed on the target page due to space limitations, it is said to overflow.