[openstack-dev] [tc] Declaring explicit minimum database versions

Monty Taylor mordred at inaugust.com
Tue Aug 15 15:59:30 UTC 2017

Hey all,

Morgan was stabbing himself in the eyes yesterday dealing with a 
database issue in keystone related to datetimes and subsecond precision. 
As usually happens when people want to stab MySQL I got roped in and my 
first thought was "dude, we landed the subsecond precision patches in 
Drizzle back in 2008 - they can't possible not be in mainline by now."

Turns out - they are, which is great. EXCEPT ... drum roll ...

We don't explicitly declare a minimum supported MySQL version, so 
updating the DDL to just set datetime subsecond precision fields seems 
like a thing we can't do.

We do imply a minimum version via our distro support policy - but we 
don't really say anything about version of externally managed database 

With that - I would like to suggest we explicitly declare that the 
minimum supported version of any given database is the minimum found in 
the union of our supported distros, which is the latest RHEL/CentOS and 
latest LTS of Ubuntu.

For the MySQL family, that currently resolves to MariaDB 5.5 / MySQL 
5.7.11, the upside being that it should be safe to depend, in any MySQL 
drivers, on any features that are included in MariaDB 5.5 or MySQL 5.7.11.

I have submitted a patch to governance to add this to our description of 
base services:


Thoughts or objections?


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