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| -rw-r--r-- | doc/src/sgml/ref/select.sgml | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/doc/src/sgml/ref/select.sgml b/doc/src/sgml/ref/select.sgml index 2624630699f..b000dbb1f5b 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 1.102 2007/11/28 15:42:31 petere Exp $ +$PostgreSQL: pgsql/doc/src/sgml/ref/select.sgml,v 1.102.2.1 2009/01/22 22:56:54 momjian Exp $ PostgreSQL documentation --> @@ -941,6 +941,22 @@ ROLLBACK TO s; anymore, in which case it will not be returned. </para> </caution> + + <caution> + <para> + Similarly, it is possible for a <command>SELECT</> command + using <literal>ORDER BY</literal> and <literal>FOR + UPDATE/SHARE</literal> to return rows out of order. This is + because <literal>ORDER BY</> is applied first. The command + orders the result, but might then block trying to obtain a lock + on one or more of the rows. Once the <literal>SELECT</> + unblocks, one of the ordered columns might have been modified + and be returned out of order. A workaround is to perform + <command>SELECT ... FOR UPDATE/SHARE</> and then <command>SELECT + ... ORDER BY</>. + </para> + </caution> + </refsect2> </refsect1> |