Database Reference
In-Depth Information
Figure 2-12.
DB Express Performance Hub: Workload
The Workload page allows you to view the application's workload profile in a very elegant way. The top-left
panel shows the user calls, parse calls, redo size, and network traffic. The Sessions panel shows you the rate of logins,
number of currently connected users, and number of open cursors.
Shaping of Network Traffic
Another interesting feature affecting the infrastructure services required to run the Oracle database are related to
network compression and a change in the maximum size of the Session Data Unit (SDU) size. New parameters in
the sqlnet.ora file allow you enable or disable compression. You need to set sqlnet.compression to “on” to enable
compression if you have the correct license for this feature. Data Guard streaming redo is exempt from this parameter
by the way, but that has little relevance: Data Guard has been able to compress archived logs for gap resolution since
11.1. Oracle 11.2 extended the scope of the compression to redo transmission.
If network compression is enabled via sqlnet.ora then you have the option to further define the aggressiveness
of the compression. The parameter sqlnet.compression_levels can take two values: low and high. It is needless to say
that a higher compression ratio comes at the cost of increased CPU consumption. To alleviate that effect it is possible
to define a threshold in bytes for data compression. Only if the size of the data sent over the wire exceeds the threshold
will the database server enable its compression algorithms. The default is to leave anything at less than 1024
bytes alone.
Threaded Architecture
There have been only two major forms of implementation in Oracle's recent releases. One was the all-threaded model
for the Windows platform, and the other one was the process architecture for the UNIX world. Beginning with 12c
the UNIX world can benefit from a multi-threaded architecture as well. This is a dramatic change that requires the
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