Hey list - It appears that MariaDB as of version 10.2 has made an enhancement that overall is great and fairly historic in the MySQL community, they've made CHECK constraints finally work. For all of MySQL's existence, you could emit a CREATE TABLE statement that included CHECK constraint, but the CHECK phrase would be silently ignored; there are no actual CHECK constraints in MySQL.
Mariadb 10.2 has now made CHECK do something! However! the bad news! They have decided that the CHECK constraint against a single column should not be implicitly dropped if you drop the column [1]. In case you were under the impression your SQLAlchemy / oslo.db project doesn't use CHECK constraints, if you are using the SQLAlchemy Boolean type, or the "ENUM" type without using MySQL's native ENUM feature (less likely), there's a simple CHECK constraint in there. So far the Zun project has reported the first bug on Alembic [2] that they can't emit a DROP COLUMN for a boolean column. In [1] I've made my complete argument for why this decision on the MariaDB side is misguided. However, be on the lookout for boolean columns that can't be DROPPED on some environments using newer MariaDB. Workarounds for now include: 1. when using Boolean(), set create_constraint=False 2. when using Boolean(), make sure it has a "name" to give the constraint, so that later you can DROP CONSTRAINT easily 3. if not doing #1 and #2, in order to drop the column you need to use the inspector (e.g. from sqlalchemy import inspect; inspector = inspect(engine)) and locate all the CHECK constraints involving the target column, and then drop them by name. [1] https://jira.mariadb.org/browse/MDEV-11114 [2] https://bitbucket.org/zzzeek/alembic/issues/440/cannot-drop-boolean-column-in-mysql __________________________________________________________________________ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev