[DBAL-920] Use PDO::PGSQL_ATTR_DISABLE_PREPARES by default

lib/Doctrine/DBAL/Driver/PDOPgSql/Driver.php

@@ -37,15 +37,21 @@ class Driver extends AbstractPostgreSQLDriver
     public function connect(array $params, $username = null, $password = null, array $driverOptions = array())
     {
         try {
-            return new PDOConnection(
+            $pdo = new PDOConnection(
                 $this->_constructPdoDsn($params),
                 $username,
                 $password,
                 $driverOptions
             );
+
+            if (PHP_VERSION_ID >= 50600) {
+                $pdo->setAttribute(\PDO::PGSQL_ATTR_DISABLE_PREPARES, true);
+            }
         } catch (PDOException $e) {
             throw DBALException::driverException($this, $e);
         }
+
+        return $pdo;
     }
 
     /**