----- Original Message ----- > From: "Monsyne Dragon" <mdra...@rackspace.com> > To: "Dan Prince" <dpri...@redhat.com> > Cc: "Sean Dague" <sda...@linux.vnet.ibm.com>, > "<openstack@lists.launchpad.net>" <openstack@lists.launchpad.net> > Sent: Friday, April 27, 2012 1:46:03 PM > Subject: Re: [Openstack] database migration cleanup > > Even better, what would it take to try using Alembic? > (http://alembic.readthedocs.org/en/latest/front.html#project-homepage)
>From the Alembic docs site: "Note that Alembic is still in alpha status." I would guess we'd want the project to be in at least a beta (stable API) state before we committed to using it, etc. > > It's a big improvement over sqlalchemy. Amongst other things, > migrations are not numbered, they are linked by dependancy, and run > in topological-sort order. That there eliminates alot of "my > migration number got taken... again..." problems. To be clear Alembic would be a potential replacement for python-migrate. Not Sqlalchemy right? Looks like an interesting project but I'm not convinced it is worth switching over to as our default at this time. > On Apr 27, 2012, at 10:47 AM, Dan Prince wrote: > > > > > > > ----- Original Message ----- > >> From: "Sean Dague" <sda...@linux.vnet.ibm.com> > >> To: openstack@lists.launchpad.net > >> Sent: Friday, April 27, 2012 10:21:17 AM > >> Subject: Re: [Openstack] database migration cleanup > >> > >> On 04/26/2012 03:24 PM, Dan Prince wrote: > >> <snip> > >>> I think this scheme would support users who follow stable > >>> releases > >>> as well as users who follow trunk very closely. > >>> > >>> We talked about this at the conference but I thought this issue > >>> might be near and dear to some of our end users so it was worth > >>> discussing on the list. > >>> > >>> What are general thoughts on this approach? > >> > >> Is there any support in sqlalchemy, or related tools, to handle > >> migrations the way rails does, where a schema file is created at > >> the > >> end > >> of every migration? It would be ideal if we both had a full > >> migration > >> history, as well as a short cut at any snap shot to get to the > >> end. > > > > Ah. Yes, the Rails schema.rb. I looked around for just this sort of > > thing and didn't find much. Python-migrate has some "experimental" > > support for generating models and I did make use of that > > initially. See 'create_model' below: > > > > > > [root@nova1 migrate_repo]# python ./manage.py --repository=./ > > --url=mysql://nova:password@localhost/nova > > Usage: manage.py COMMAND ... > > > > Available commands: > > compare_model_to_db - compare MetaData against the > > current database state > > create - create an empty repository at the > > specified path > > create_model - dump the current database as a > > Python model to stdout > > db_version - show the current version of the > > repository under version control > > downgrade - downgrade a database to an earlier > > version > > drop_version_control - removes version control from a > > database > > help - displays help on a given command > > make_update_script_for_model - create a script changing the old > > MetaData to the new (current) MetaData > > manage - creates a Python script that runs > > Migrate with a set of default values > > script - create an empty change Python > > script > > script_sql - create empty change SQL scripts for > > given database > > source - display the Python code for a > > particular version in this repository > > test - performs the upgrade and downgrade > > command on the given database > > update_db_from_model - modify the database to match the > > structure of the current MetaData > > upgrade - upgrade a database to a later > > version > > version - display the latest version > > available in a repository > > version_control - mark a database as under this > > repository's version control > > > > ---- > > > > python-migrate's 'create_model' does not however give you something > > that exactly matches the schema you'd get by running the all the > > migrations. So auto generation doesn't appear to be an option > > right now. It would be nice to contribute python-migrate in this > > regard and get better support for model generation, etc. Maybe a > > good long term goal? > > > > Dan > > > > > >> > >> -Sean > >> > >> -- > >> Sean Dague > >> IBM Linux Technology Center > >> email: slda...@us.ibm.com > >> alt-email: sda...@linux.vnet.ibm.com > >> > >> > >> _______________________________________________ > >> Mailing list: https://launchpad.net/~openstack > >> Post to : openstack@lists.launchpad.net > >> Unsubscribe : https://launchpad.net/~openstack > >> More help : https://help.launchpad.net/ListHelp > >> > > > > _______________________________________________ > > Mailing list: https://launchpad.net/~openstack > > Post to : openstack@lists.launchpad.net > > Unsubscribe : https://launchpad.net/~openstack > > More help : https://help.launchpad.net/ListHelp > > -- > Monsyne M. Dragon > OpenStack/Nova > cell 210-441-0965 > work x 5014190 > > _______________________________________________ Mailing list: https://launchpad.net/~openstack Post to : openstack@lists.launchpad.net Unsubscribe : https://launchpad.net/~openstack More help : https://help.launchpad.net/ListHelp
