You still need to monitor those aspects of the database that are critical to its success, such
as the free space in tablespaces. However, the performance of distributed databases cannot be
measured except as part of the performance of the network that supports them. Therefore, all
performance-related tests, such as stress tests, must be coordinated with the network management
staff. That staff may also be able to verify the effectiveness of your attempts to reduce the database
load on the network.
The performance of the individual hosts can usually be monitored via a network monitoring
package. This monitoring is performed in a top-down fashion, from network to host to database.
Use the monitoring system described in Chapter 6 as an extension to the network and host monitors.
Tuning Distributed Databases
When you??™re tuning a stand-alone database, the goal is to reduce the amount of time it takes to
find data. As described in Chapter 8, you can use a number of database structures and options to
increase the likelihood that the data will be found in the buffer cache or via an index.
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Chapter 17: Managing Distributed Databases 633
When working with distributed databases, you have an additional consideration: Because
data is now not only being retrieved but also being shipped across the network, the performance
of a query is made up of the performance of these two steps. You must therefore consider the ways
in which data is being transferred across the network, with a goal of reducing the network traffic.
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