diff --git a/stackrc b/stackrc
index fb84366..a8467ba 100644
--- a/stackrc
+++ b/stackrc
@@ -52,6 +52,18 @@
     ENABLED_SERVICES+=,rabbit,tempest,mysql
 fi
 
+# SQLAlchemy supports multiple database drivers for each database server
+# type. For example, deployer may use MySQLdb, MySQLConnector, or oursql
+# to access MySQL database.
+#
+# When defined, the variable controls which database driver is used to
+# connect to database server. Otherwise using default driver defined for
+# each database type.
+#
+# You can find the list of currently supported drivers for each database
+# type at: http://docs.sqlalchemy.org/en/rel_0_9/core/engines.html
+# SQLALCHEMY_DATABASE_DRIVER="mysqldb"
+
 # Global toggle for enabling services under mod_wsgi. If this is set to
 # ``True`` all services that use HTTPD + mod_wsgi as the preferred method of
 # deployment, will be deployed under Apache. If this is set to ``False`` all