Databases Reference
In-Depth Information
Although a larger packet size is typically the best choice for performance,
this isn't always the case. If your application sends queries that only retrieve small
result sets, a small packet size can work well. For example, an ATM banking
application typically sends and receives many packets that contain a small
amount of data, such as a withdrawal amount, a deposit amount, and a new bal-
ance. A result set that contains only one or two rows of data may not completely
fill a larger packet. In this case, using larger packets wouldn't improve perfor-
mance. In contrast, a reporting application that retrieves large result sets with
thousands of rows performs best when using larger packets.
Performance Tip
If your application sends queries that retrieve large amounts of data, tune
your database server packet size to the maximum size, and tune your
database driver to match the maximum size used by the database server.
Often, we talk about database access as if the client is always local to the database
server, perhaps in the same building connected by a LAN. However, in today's
distributed computing environment, the reality is that a user working from a
client desktop in New York may retrieve data stored in a database that is located
in California, or Europe, for that matter.
For example, a database application may send a data request that travels
across a LAN, often through one or multiple routers, across a WAN, and through
more routers to reach the target database. Because the world's most popular
WAN is the Internet, an application may also need to communicate through one
or multiple Internet service provider (ISP) routers. Then the data that is
retrieved from the database must travel back along a similar path before users
even see it on their desktops.
Whether your database application accesses a database server locally on a
LAN or your data requests follow a more complicated path, how do you deter-
mine if network packets associated with your database application are using the
most efficient path?
You can use the
tracert
command (Windows) and the
traceroute
com-
mand (UNIX/Linux) to find out which network nodes the network packets
travel through on their way to a destination. In addition, by default, these
commands display a sampling of the
latency
, the time delay it takes to make a
network round trip to each node along the traced path.
