From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri, 8 Jun 2007 20:26:18 +0000 (+0000)
Subject: Add note that LIMIT without ORDER BY can produce outright nondeterministic
X-Git-Tag: REL8_3_BETA1~576
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=4213e5f0dbed36d7452f385782eeaa2c8a866173;p=postgresql

Add note that LIMIT without ORDER BY can produce outright nondeterministic
results.  Necessary due to introduction of syncscan patch.
---

diff --git a/doc/src/sgml/ref/select.sgml b/doc/src/sgml/ref/select.sgml
index 0f1ada97cb..2165a63d4a 100644
--- a/doc/src/sgml/ref/select.sgml
+++ b/doc/src/sgml/ref/select.sgml
@@ -1,5 +1,5 @@
 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/select.sgml,v 1.100 2007/05/15 19:13:55 neilc Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/select.sgml,v 1.101 2007/06/08 20:26:18 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -810,6 +810,14 @@ OFFSET <replaceable class="parameter">start</replaceable>
     to deliver the results of a query in any particular order unless
     <literal>ORDER BY</> is used to constrain the order.
    </para>
+
+   <para>
+    It is even possible for repeated executions of the same <literal>LIMIT</>
+    query to return different subsets of the rows of a table, if there
+    is not an <literal>ORDER BY</> to enforce selection of a deterministic
+    subset.  Again, this is not a bug; determinism of the results is
+    simply not guaranteed in such a case.
+   </para>
   </refsect2>
 
   <refsect2 id="SQL-FOR-UPDATE-SHARE">