Databases Reference
In-Depth Information
overhead associated with establishing a physical connection. In JDBC, the
application must use a
DataSource
object (an object implementing the
DataSource
interface) to obtain a connection to use connection pooling. So,
the application needs to be changed to use a
DataSource
object. See
“Connection Pool Model for JDBC,” page 223, for details.
•
The driver was using a 32KB database protocol packet size. In this case, a
smaller size would provide a better response time because small result sets
are being returned to the application. In this case, a 32KB packet size has too
much capacity for the amount of data being returned, which causes more
memory use than when using a smaller packet size.
When the performance of a database application is unacceptable, the first step is
to define the issue. Is the issue related to throughput, response time, scalability, or
a combination? The second step is to think through the possible causes. For
example, if response time is the issue, does your application have a memory leak
or does it perform excessive data conversions? The third step is to narrow down
the possible causes of the performance issue. You might find it helpful to trou-
bleshoot in the following order:
1.
Look at the complete picture and ask yourself the following important
question: Has anything changed in any of the components of the data-
base application deployment? If the answer is yes, start by looking at
what changed.
2.
If nothing has changed, look at the database application.
3.
If your database application does not seem to be the issue, look at your
database driver.
4.
If you are not satisfied with the performance after looking at the appli-
cation and the database driver, look at the environment where your
application is deployed.
One important fact to note is that if the database server machine is resource
bound, no amount of tuning of your applications or the database middleware
results in acceptable performance.
