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authorBruce Momjian <bruce@momjian.us>2006-01-19 22:52:20 +0000
committerBruce Momjian <bruce@momjian.us>2006-01-19 22:52:20 +0000
commitb148ce8a4a1e24cefdb5f376c0e600ad0401ae47 (patch)
treeeba16a80cfc9fa72898748942323e88d627f806f /doc/src
parent337cc41236befe5581d6a72dab9113e5cd48fecb (diff)
downloadpostgresql-b148ce8a4a1e24cefdb5f376c0e600ad0401ae47.tar.gz
postgresql-b148ce8a4a1e24cefdb5f376c0e600ad0401ae47.zip
Clarify STABLE function documentation to highlight how such functions
can be optimized.
Diffstat (limited to 'doc/src')
-rw-r--r--doc/src/sgml/xfunc.sgml16
1 files changed, 8 insertions, 8 deletions
diff --git a/doc/src/sgml/xfunc.sgml b/doc/src/sgml/xfunc.sgml
index ff461884db2..d11e32bc4c9 100644
--- a/doc/src/sgml/xfunc.sgml
+++ b/doc/src/sgml/xfunc.sgml
@@ -1,5 +1,5 @@
<!--
-$PostgreSQL: pgsql/doc/src/sgml/xfunc.sgml,v 1.107 2005/10/15 20:12:33 neilc Exp $
+$PostgreSQL: pgsql/doc/src/sgml/xfunc.sgml,v 1.107.2.1 2006/01/19 22:52:20 momjian Exp $
-->
<sect1 id="xfunc">
@@ -899,13 +899,13 @@ CREATE FUNCTION test(int, int) RETURNS int
<para>
A <literal>STABLE</> function cannot modify the database and is
guaranteed to return the same results given the same arguments
- for all calls within a single surrounding query. This category
- allows the optimizer to optimize away multiple calls of the function
- within a single query. In particular, it is safe to use an expression
- containing such a function in an index scan condition. (Since an
- index scan will evaluate the comparison value only once, not once at
- each row, it is not valid to use a <literal>VOLATILE</> function in
- an index scan condition.)
+ for all rows within a single statement. This category allows the
+ optimizer to optimize multiple calls of the function to a single
+ call. In particular, it is safe to use an expression containing
+ such a function in an index scan condition. (Since an index scan
+ will evaluate the comparison value only once, not once at each
+ row, it is not valid to use a <literal>VOLATILE</> function in an
+ index scan condition.)
</para>
</listitem>
<listitem>