Index: database.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/database/database.inc,v
retrieving revision 1.57
diff -u -r1.57 database.inc
--- database.inc	1 Jul 2009 08:11:27 -0000	1.57
+++ database.inc	2 Jul 2009 21:17:59 -0000
@@ -2460,6 +2460,35 @@
 }
 
 /**
+ * Helper function to get duration lag from variable
+ * and set the session variable that contains the lag.
+ */
+function db_ignore_slave() {
+  $use_slave = &drupal_static(__FUNCTION__);
+  // This statement will only be executed the first time through when $use_slave
+  // is NULL, since it will be set to TRUE or FALSE at the end.
+  if ($use_slave == NULL) {
+    $connection_info = Database::getConnectionInfo();
+      // Only set ignore_slave_server if there are slave servers
+     // being used, which is assumed if there are more than one.    
+    if (count($connection_info) > 1) {
+      // Five minutes is long enough to allow the slave to break and resume
+      // interrupted replication without causing problems on the Drupal site
+      // from the old data.
+      $duration = variable_get('maximum_replication_lag', 300);
+      // Set session variable with amount of time to delay before using slave.
+      $_SESSION['ignore_slave_server'] = REQUEST_TIME + $duration;
+      // Set cached variable to true to indicate that slave is being used.
+      $use_slave = TRUE;
+    }
+    else {
+      // Set cached variable to false since there is no slave being used.
+      $use_slave = FALSE;
+    }
+  }        
+}
+
+/**
  * @ingroup database-legacy
  *
  * These functions are no longer necessary, as the DatabaseStatementInterface interface
@@ -2688,19 +2717,5 @@
 }
 
 /**
- * Helper function to get duration lag from variable
- * and set the session variable that contains the lag.
- */
-function db_ignore_slave() {
-  // Five minutes is long enough to allow the slave to break and resume
-  // interrupted replication without causing problems on the Drupal site
-  // from the old data.
-  $duration = variable_get('maximum_replication_lag', 300);
-  
-  // Set session variable with amount of time to delay  before using slave.
-  $_SESSION['ignore_slave_server'] = REQUEST_TIME + $duration;
-}
-
-/**
  * @} End of "ingroup database-legacy".
  */