Once data has been stored in a table, either of the following two page search modes can be used to search the storage area:
- New page allocate mode
When the final page of a used segment becomes full, a new unused segment is allocated. If no unused pages remain in the RDAREA, free space to store the data is searched for in used pages from the beginning of the used segments.
When there are unused segments, storage efficiency will not improve, but processing can be performed at high speed. However, performance will drop significantly when there are no more unused segments.
- Free page reuse mode
When the final page of a used segment becomes full, free space is searched for in the used pages of the used segments before any unused segments are allocated. The search start position is then remembered for next search, and the subsequent search for free space begins from that point.
Storage efficiency will improve even when there are unused segments because free space is searched for and data is then stored, but this also entails overhead.