Databases Reference
In-Depth Information
For the same reason, make sure that your test machines are “clean.” Only run
software that your application requires. Other applications running at the same
time or in the background can profoundly influence test results. For example, if a
virus-checking routine kicks off during a benchmarking run, it can slow perfor-
mance significantly.
To design a good benchmark, you must have a solid understanding of the work-
load your application will deal with in the production environment. Ask yourself
the following questions:
•
What tasks does my application commonly perform? Which tasks are signif-
icant enough to measure?
•
How many users does my application accommodate during peak traffic
times?
Duplicating your real-world workload to an exact degree can be impractical
or impossible, but it's important to emulate the essential characteristics of your
workload and represent them accurately. For example, if you have a customer
service application that typically performs the following actions, your test appli-
cation should perform the same type of actions using the same data characteris-
tics:
•
Retrieves the customer record (one large row) from a table
•
Retrieves invoices (multiple small rows) from another table
•
Updates an invoice (one small row) as part of a transaction
Emulate the peak traffic that your application encounters in the production
environment. For example, suppose that you have an intranet application that
has 500 users, many working in an office on the West Coast of the United States.
At 8:00 a.m. PST on a typical workday, as few as 20 users are active, whereas at
3:00 p.m. PST, approximately 400 users are active. In this case, design the
benchmark to emulate 400 (or more) users. Commercial load test tools such as
HP's LoadRunner allow you to easily emulate many concurrent users.
Not all tasks that a database application performs are equally important. For
example, a mail-order company that accepts orders over the phone may require a
quick response time when referencing inventory availability to minimize the wait
for the customer on the phone. That same company may not care as much about
