||Oracle Tips by Burleson
Oracle 10g Simplified Shared Server Configuration
In Oracle 10g, you no longer need to set as many
initialization parameters for shared server environments. In fact,
you only need to set one parameter if you are using TCP/IP as your
communication protocol, and the rest of the settings are now managed
Server Initialization Parameters
The following initialization parameters in
Oracle 10g control shared server operation:
shared_servers – This parameter
specifies the initial number of shared servers to start and the
minimum number of shared servers to keep. This is the only required
parameter for using shared servers. Setting this to a non-zero value
automatically specifies shared server.
max_shared_servers – This parameter
specifies the maximum number of shared servers that can run
simultaneously. Once shared server is initialized, the Oracle system
will increase the number of shared servers up to this value as
shared_server_sessions -- This parameter
specifies the total number of shared server user sessions that can
run simultaneously. Setting this parameter enables you to reserve
user sessions for dedicated servers. For example, if the sessions
parameter is set at 1000 and you set shared_server_sessions to 900,
then 100 dedicated sessions are available, even if all 900 shared
sessions are in use.
dispatchers – This parameter configures
dispatcher processes in the shared server architecture. One
dispatcher is always configured by default for the TCP/IP protocol,
even if the parameter is not explicitly specified.
max_dispatchers – This parameter
specifies the maximum number of dispatcher processes that can run
simultaneously. According to the Oracle 10g manuals, this parameter
can be ignored for now. It will only be useful in a future release
when the number of dispatchers is auto-tuned, according to the
number of concurrent connections.
circuits – This parameter specifies the
total number of virtual circuits that are available for inbound and
outbound network sessions.
Even though there are six initialization
parameters, shared server is enabled by setting one parameter and is
turned on if the shared_servers initialization parameter is set to a
value greater than 0. This is all that is required. The other shared
server initialization parameters do not need to be set. Because the
shared server parameter requires at least one dispatcher to work, a
dispatcher is brought up automatically even when no dispatcher has
Using SQL*Plus or OEM, the shared server features can be started
dynamically by setting the shared_servers parameter to a nonzero
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