The paging option of shared pools can have a significant impact
on the performance of reading and changing database files.
- A paging option of *FIXED causes the program to minimize the amount of
memory it uses by:
- Transferring data from auxiliary storage to main memory in smaller blocks
- Writing file changes (updates to existing records or newly added records)
to auxiliary storage frequently
This option allows the system to perform much like it did
before the paging option was added.
- A paging option of *CALC might improve how the program performs when it
reads and updates database files. In cases where there is sufficient memory
available within a shared pool, the program might:
- Transfer larger blocks of data to memory from auxiliary storage.
- Write changed data to auxiliary storage less frequently.
The paging operations done on database files vary dynamically based on
file use and memory availability. Frequently referenced files are more likely
to remain resident than those less often accessed. The memory is used somewhat
like a cache for popular data. The overall number of I/O operations might
be reduced using the *CALC paging option.