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authorTom Lane <tgl@sss.pgh.pa.us>2007-06-08 20:26:18 +0000
committerTom Lane <tgl@sss.pgh.pa.us>2007-06-08 20:26:18 +0000
commit4213e5f0dbed36d7452f385782eeaa2c8a866173 (patch)
treea9d9250258d5da3774c3d028afacf0f2735d08b5 /doc/src
parenta3e3389913b47cc600d0588fe395da976b61806c (diff)
Add note that LIMIT without ORDER BY can produce outright nondeterministic
results. Necessary due to introduction of syncscan patch.
Diffstat (limited to 'doc/src')
-rw-r--r--doc/src/sgml/ref/select.sgml10
1 files changed, 9 insertions, 1 deletions
diff --git a/doc/src/sgml/ref/select.sgml b/doc/src/sgml/ref/select.sgml
index 0f1ada97cb6..2165a63d4a1 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">