From 878fdcb843e087cc1cdeadc987d6ef55202ddd04 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Mon, 2 Mar 2015 14:21:41 -0500
Subject: pgbench: Add a real expression syntax to \set
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Previously, you could do \set variable operand1 operator operand2, but
nothing more complicated.  Now, you can \set variable expression, which
makes it much simpler to do multi-step calculations here.  This also
adds support for the modulo operator (%), with the same semantics as in
C.

Robert Haas and Fabien Coelho, reviewed by Álvaro Herrera and
Stephen Frost
---
 doc/src/sgml/pgbench.sgml | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

(limited to 'doc/src')

diff --git a/doc/src/sgml/pgbench.sgml b/doc/src/sgml/pgbench.sgml
index 7d203cda84c..16b82a3bbe0 100644
--- a/doc/src/sgml/pgbench.sgml
+++ b/doc/src/sgml/pgbench.sgml
@@ -751,22 +751,25 @@ pgbench <optional> <replaceable>options</> </optional> <replaceable>dbname</>
   <variablelist>
    <varlistentry>
     <term>
-     <literal>\set <replaceable>varname</> <replaceable>operand1</> [ <replaceable>operator</> <replaceable>operand2</> ]</literal>
+     <literal>\set <replaceable>varname</> <replaceable>expression</>
     </term>
 
     <listitem>
      <para>
-      Sets variable <replaceable>varname</> to a calculated integer value.
-      Each <replaceable>operand</> is either an integer constant or a
-      <literal>:</><replaceable>variablename</> reference to a variable
-      having an integer value.  The <replaceable>operator</> can be
-      <literal>+</>, <literal>-</>, <literal>*</>, or <literal>/</>.
+      Sets variable <replaceable>varname</> to an integer value calculated
+      from <replaceable>expression</>.
+      The expression may contain integer constants such as <literal>5432</>,
+      references to variables <literal>:</><replaceable>variablename</>,
+      and expressions composed of unary (<literal>-</>) or binary operators
+      (<literal>+</>, <literal>-</>, <literal>*</>, <literal>/</>, <literal>%</>)
+      with their usual associativity, and parentheses.
      </para>
 
      <para>
-      Example:
+      Examples:
 <programlisting>
 \set ntellers 10 * :scale
+\set aid (1021 * :aid) % (100000 * :scale) + 1
 </programlisting></para>
     </listitem>
    </varlistentry>
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