Seagate ST43401N/ND Przewodnik Instalacji Pobierz pdf (Strona 95)

CHAPTER 7 Test: Ensuring Stability and Performance

Result Handling

You can capture query results by fetching the entire result set back to the client

and binding it to local variables. Outputting results to a file may increase your

time by requiring additional file I/O and operating system buffering.

Time Measurement

Time measurement is especially important in multi-tiered applications where a

bottleneck could occur at any level. Generally, you should time database

transactions, not business functions. Start at transaction “send” and stop at the

last row processed in the result set. Logical business operations can be

aggregated later.

Granularity is important for problem identification and resolution. Important

measurements to take include:

• Throughput (number of transactions per second/minute/hour)

• Average and maximum response time by transaction

• A histogram of response time ranges by transaction. For example:

• Less than 1 second

• Between 1 and 2 seconds

• Between 2 and 3 seconds

• Over 3 seconds

Runtime Data Generation

When using runtime-generated data, skewed keys may be a problem. Selects

may show an unrealistically high cache hit rate, and inserts, updates, and

deletes may appear to have concurrency problems. To avoid these problems,

use the entire range of key values in your tests, unless you are trying to recreate

a particular business situation.

Using a separate file for each transaction can prevent skewing; however, it

requires additional code to synchronize users. Using a separate file for each

user is more work to create but also prevents skewing.

Using a memory generator works well to prevent skewing and makes the test

easy to administer. However, the benchmark is then not 100% repeatable.

1 2 ... 90 91 92 93 94 95 96 97 98 99 100 ... 145 146

Brak uwag

Seagate ST43401N/ND Przewodnik Instalacji Strona 95