From 1c155c8dfb0bd5576f3865ef44818d6a91b24be0 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Wed, 20 Apr 2005 22:19:58 +0000
Subject: [PATCH] Add note clarifying that indexes that support ordered scans
had better allow clauseless scans.
---
doc/src/sgml/indexam.sgml | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/doc/src/sgml/indexam.sgml b/doc/src/sgml/indexam.sgml
index ef1e37a8260..9a84509f749 100644
--- a/doc/src/sgml/indexam.sgml
+++ b/doc/src/sgml/indexam.sgml
@@ -1,5 +1,5 @@
<!--
-$PostgreSQL: pgsql/doc/src/sgml/indexam.sgml,v 2.3 2005/03/27 23:52:51 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/indexam.sgml,v 2.4 2005/04/20 22:19:58 tgl Exp $
-->
<chapter id="indexam">
@@ -109,7 +109,8 @@ $PostgreSQL: pgsql/doc/src/sgml/indexam.sgml,v 2.3 2005/03/27 23:52:51 tgl Exp $
such a scan should include null rows. In practice this means that
indexes that support ordered scans (have <structfield>amorderstrategy</>
nonzero) must index nulls, since the planner might decide to use such a
- scan as a substitute for sorting. Another restriction is that an index
+ scan as a substitute for sorting. Such indexes must also be willing to
+ run a scan with no scan keys at all. Another restriction is that an index
access method that supports multiple index columns <emphasis>must</>
support indexing null values in columns after the first, because the planner
will assume the index can be used for queries on just the first
--
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