Disk I/O
The slowest thing in any computer system is the disk I/O. Disk I/O almost always takes more time than any other system processing activity. When we begin concentrating our design efforts on efficiency, focus first on minimizing disk I/O.
The most critical elements are the design of the keys, the number of keys, the design of the SIFT fields, the number of SIFT fields, the design of the filters, and the frequency of accesses of data (especially FlowFields). If our system is going to have five or ten users processing a few thousand order lines per day, and if our system is not heavily modified, we probably won't have much trouble. But if we are installing a system with one or more of the following attributes, any of which can have a significant effect on the amount of disk I/O, we will need to be very careful with our design and implementation:
- Large concurrent user count
- High transaction volumes, especially in data being Posted
- Large stored data volumes, especially that...
