Clarify the difference between "prepared mode" and other query modes.
Discussion: https://postgr.es/m/
20181030.103654.
2249812451112831300.t-ishii@sraoss.co.jp
Reviewed by: Fabien Coelh and Alvaro Herrera.
<para><literal>prepared</literal>: use extended query protocol with prepared statements.</para>
</listitem>
</itemizedlist>
+
+ Because in "prepared" mode <application>pgbench</application> reuses
+ the parse analysis result for the second and subsequent query
+ iteration, <application>pgbench</application> runs faster in the
+ prepared mode than in other modes.
+ </para>
+ <para>
The default is simple query protocol. (See <xref linkend="protocol"/>
for more information.)
</para>