diff --git a/doc/source/configuration.rst b/doc/source/configuration.rst
index 62571e0..45f4ffe 100644
--- a/doc/source/configuration.rst
+++ b/doc/source/configuration.rst
@@ -326,23 +326,29 @@
 Database Backend
 ----------------
 
-Support for the MySQL database backend is included. Addition database backends
-may be available via external plugins. Enabling of disabling MySQL is handled
-via the usual service functions and ``ENABLED_SERVICES``. For example, to
-disable MySQL in ``local.conf``::
+Multiple database backends are available. The available databases are defined
+in the lib/databases directory.
+``mysql`` is the default database, choose a different one by putting the
+following in the ``localrc`` section::
 
   disable_service mysql
+  enable_service postgresql
+
+``mysql`` is the default database.
 
 RPC Backend
 -----------
 
-Support for a RabbitMQ RPC backend is included. Additional RPC backends may be
-available via external plugins.  Enabling or disabling RabbitMQ is handled via
-the usual service functions and ``ENABLED_SERVICES``. For example, to disable
-RabbitMQ in ``local.conf``::
+Support for a RabbitMQ RPC backend is included. Additional RPC
+backends may be available via external plugins.  Enabling or disabling
+RabbitMQ is handled via the usual service functions and
+``ENABLED_SERVICES``.
+
+Example disabling RabbitMQ in ``local.conf``::
 
   disable_service rabbit
 
+
 Apache Frontend
 ---------------
 
diff --git a/doc/source/zuul_ci_jobs_migration.rst b/doc/source/zuul_ci_jobs_migration.rst
index 66f8251..17e7e16 100644
--- a/doc/source/zuul_ci_jobs_migration.rst
+++ b/doc/source/zuul_ci_jobs_migration.rst
@@ -302,7 +302,10 @@
      - This will probably be implemented on ironic side.
    * - DEVSTACK_GATE_POSTGRES
      - Legacy
-     - This has no effect in d-g.
+     - This flag exists in d-g but the only thing that it does is
+       capture postgres logs. This is already supported by the roles
+       in post, so the flag is useless in the new jobs. postgres
+       itself can be enabled via the devstack_service job variable.
    * - DEVSTACK_GATE_ZEROMQ
      - Legacy
      - This has no effect in d-g.