Explicitly added driver name variable in each DB driver, based on this bug report: #4436
diff --git a/system/database/drivers/postgre/postgre_driver.php b/system/database/drivers/postgre/postgre_driver.php
index aada164..c5c70a7 100644
--- a/system/database/drivers/postgre/postgre_driver.php
+++ b/system/database/drivers/postgre/postgre_driver.php
@@ -30,6 +30,8 @@
  */

 class CI_DB_postgre_driver extends CI_DB {

 

+	var $dbdriver = 'postgre';

+

 	/**

 	 * The syntax to count rows is slightly different across different

 	 * database engines, so this string appears in each driver and is