Sybase 12.4.2 manual Introduction to performance terms, Designing for performance, 419

C H A P T E R 1 2 Managing System Resources

About this chapter	This chapter describes the way Adaptive Server IQ uses memory, disk I/O,
	and CPUs, and the relationships among these factors. It also explains how
	the DBA can tune performance by adjusting resource usage.
	The suggestions in this chapter are generic. You need to adjust them to suit
	your hardware and software configuration.

Introduction to performance terms

Performance is the measure of efficiency of a computerized business application, or of multiple applications running in the same environment. It is usually measured in response time and throughput.

Response time is the time it takes for a single task to complete. It is affected by:

•Reducing contention and wait times, particularly disk I/O wait times

•Using faster components

•Reducing the amount of time the resources are needed (this is the same as increasing concurrency)

Throughput refers to the volume of work completed in a fixed time period. Throughput is commonly measured in transactions per second (tps), but can be measured per minute, per hour, per day, and so on.

Designing for performance

Most gains in performance derive from good database design, thorough query analysis, and appropriate indexing. The largest performance gains can be realized by establishing a good design and by choosing the correct indexing strategy.

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