Comment 12 for bug 993663

** Impact **

Create a utf8 version of the dns_domains table.

    The old dns_domains table was encoded in the 'latin1'
    charset and has its primary key length set to 512.
    This is too long to be a valid pkey in a proper 'utf8' encoded
    table and seems to cause a slew of errors like:

    1) Dumping a database with mysqldump and trying to import it fails
    because this table is latin1 but fkeys to utf8 tables (projects).

    2) Trying to alter the old dns_domains table fails with errors
    like:
    mysql> ALTER TABLE dns_domains DROP PRIMARY KEY;
    ERROR 1025 (HY000): Error on rename of './nova/#sql-6cf_855'....

    This patch creates an Essex fix that re-creates the dns_domains
    table with a shorter 'domain' column which works with the utf8
    charset. This database upgrade will run on MySQL databases only
    which have a dns_domains table with a domain column length of
    VARCHAR(512).

    Fixes LP Bug #993663 on Essex.

** Development Fix **

This is fixed in the development trunk at https://review.openstack.org/7139 and in quantal

** Stable Fix **

This is fixed in the stable/essex branch at https://review.openstack.org/8356.

** Test Case **

1. Make a database backup of the nova database.
2. Drop the nova database.
3. Try to restore the database.

** Regression Impact **

Minimal this has been tested in the openstack-ci lab.