Comment 3 for bug 1443562

seems you are using juno version code
looks to me the commit add the support

commit ba407e33d3fedd2d283ba8752ff592fb3e0e2d43
Author: Dheeraj Gupta <email address hidden>
Date: Tue Jan 27 11:55:55 2015 +0000

    Add support for multiple database engines

and we got following at nova.conf.sample
2042 [database]
2043
2044 #
2045 # Options defined in nova.db.sqlalchemy.api

do you have chance to take a look at latest rpms ? I am not sure whether backport this to juno will be accepted or not...