-<!-- $PostgreSQL: pgsql/doc/src/sgml/rules.sgml,v 1.40 2005/01/23 00:30:18 momjian Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/rules.sgml,v 1.41 2005/01/29 23:45:36 tgl Exp $ -->
<chapter id="rules">
<title>The Rule System</title>
The query trees generated from rule actions are thrown into the
rewrite system again, and maybe more rules get applied resulting
in more or less query trees.
- So the query trees in the rule actions must have either a different command type
- or a different result relation, otherwise, this recursive process will end up in a loop.
- There is a fixed recursion limit of currently 100 iterations.
- If after 100 iterations there are still update rules to apply, the
- rule system assumes a loop over multiple rule definitions and reports
- an error.
+ So a rule's actions must have either a different
+ command type or a different result relation than the rule itself is
+ on, otherwise this recursive process will end up in an infinite loop.
+ (Recursive expansion of a rule will be detected and reported as an
+ error.)
</para>
<para>