diff options
| -rw-r--r-- | doc/src/sgml/ref/declare.sgml | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/doc/src/sgml/ref/declare.sgml b/doc/src/sgml/ref/declare.sgml index 641971149ac..e93b4cf594d 100644 --- a/doc/src/sgml/ref/declare.sgml +++ b/doc/src/sgml/ref/declare.sgml @@ -1,5 +1,5 @@ <!-- -$PostgreSQL: pgsql/doc/src/sgml/ref/declare.sgml,v 1.46 2009/04/10 17:56:21 tgl Exp $ +$PostgreSQL: pgsql/doc/src/sgml/ref/declare.sgml,v 1.47 2009/06/10 19:21:37 tgl Exp $ PostgreSQL documentation --> @@ -228,6 +228,20 @@ DECLARE <replaceable class="parameter">name</replaceable> [ BINARY ] [ INSENSITI <literal>SCROLL</literal> may not be specified in this case. </para> + <caution> + <para> + Scrollable and <literal>WITH HOLD</literal> cursors may give unexpected + results if they invoke any volatile functions (see <xref + linkend="xfunc-volatility">). When a previously fetched row is + re-fetched, the functions might be re-executed, perhaps leading to + results different from the first time. One workaround for such cases + is to declare the cursor <literal>WITH HOLD</literal> and commit the + transaction before reading any rows from it. This will force the + entire output of the cursor to be materialized in temporary storage, + so that volatile functions are executed exactly once for each row. + </para> + </caution> + <para> If the cursor's query includes <literal>FOR UPDATE</> or <literal>FOR SHARE</>, then returned rows are locked at the time they are first |