The FairCom DB data cache uses the following approach to cache data record images:
The nature of this approach can be modified. Set MPAGE_CACHE to a value greater than zero, N, to store records falling within N+2 cache pages entirely within the cache. The default value is zero, behaves as described above.
Note: Setting MPAGE_CACHE greater than zero does NOT ensure faster system operation. It is more likely to be slower than faster. It does cause more of a record to be in cache, but there is increased overhead managing each individual cache page. The cache pages for consecutive segments of a record (where a segment fills a cache page) are completely independent of each other. They are not stored in consecutive memory and I/O is performed separately for each cache page. This configuration option should only be used for special circumstances with careful, realistic testing.
Note: Even a record smaller than a single cache page may require two cache pages because the record position is generally not aligned on a cache page boundary.