+ This filter implements global sharing of
+ result sets (i.e. between threads and therefore between
+ clients), yielding performance improvements especially when
+ incoming requests are from a stateless environment such as a
+ web-server, in which the client process representing a session
+ might be any one of many.
+ It performs the following actions:
+ <itemizedlist>
+ <listitem>
+ <para>
+ Reduce the number of backend server sessions.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ Reduce the number of initializations with backend servers.
+ </para>
+ </listitem>
+ <listitem>
+ <para>
+ Optimize the use of result-sets.
+ </para>
+ </listitem>
+ </itemizedlist>
+ </para>
+ <para>
+ Configurable values:
+ <variablelist>
+ <varlistentry><term>Session TTL</term>
+ <listitem>
+ <para>
+ When a backend session is idle for more than this amount of
+ time, given in seconds, it will be closed. Default value
+ is 90 seconds.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry><term>Session max</term>
+ <listitem>
+ <para>
+ Specifiers maximum number of sessions to any particular
+ target. If this number (limit) is reached, the session_shared
+ module will re-use result sets even if TTL is not met.
+ Failing that the session_shared will return a diagnostic.
+ Default value is 100 sessions.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry><term>Result-Set TTL</term>
+ <listitem>
+ <para>
+ When a backend session result-set is not in use for more than this
+ amount of time, given in seconds, it will be deleted/reused.
+ Default value is 30 seconds.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry><term>Result-Set max</term>
+ <listitem>
+ <para>
+ This specifies the maximum number of result-sets in use by
+ a backend. The number only applies to targets/servers with named
+ result sets. Targets that do not support named result sets
+ may only have one active result set. Default value is 10.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry><term>Result-Set restart</term>
+ <listitem>
+ <para>
+ Boolean which specifies whether session_shared should to try to
+ recover a failed search. If a search results in diagnostic 2:
+ temporary system error, or a negative hit count, the search
+ will be performed once again on another or new Z39.50 session.
+ Default value is true (enabled).
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>