The Query Tree

Date: Sun, 13 Apr 2003 17:43:49 -0600
From: Sean Reifschneider <jafo@tummy.com>
To: pgsql-docs@postgresql.org
Subject: Docs patch to note that rules only get run once per query.
Message-ID: <20030413234349.GF7507@tummy.com>
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I've made the following patch to the current CVS docs.  This is to
explain some confusion I ran into when trying to use rules.  After
reading the documentation on rules, I was expecting my rule to get run
at the end of a query where I deleted multiple rows, not after the first
row was deleted, then not any further.

I think the below text makes it more clear that this may happen and is
not a bug.

Sean

--- rules.sgml.old	2003-04-13 16:58:27.000000000 -0600
+++ rules.sgml	2003-04-13 17:26:53.000000000 -0600
@@ -32,6 +32,15 @@
      linkend="ONG90">.
 </para>
 
+<Note>
+ <Para>
+  Note that rules are only invoked once per query.  This may be a problem
+  in instances where the rule is updating a table based on another table's
+  contents, and you do a delete or update that changes multiple rows.  In
+  this case, you will have to use a trigger.
+ </Para>
+</Note>
+
 <Sect1 id="querytree">
 <Title>The Query Tree</Title>
 
-- 
 Do one thing every day that scares you.
                 -- Mary Schmich
Sean Reifschneider, Inimitably Superfluous <jafo@tummy.com>
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