Bug 890189

Summary: Better support for database schema migrations
Product: Red Hat OpenStack Reporter: Perry Myers <pmyers>
Component: RFEsAssignee: David Ripton <dripton>
Status: CLOSED WONTFIX QA Contact: Yaniv Kaul <ykaul>
Severity: medium Docs Contact:
Priority: high    
Version: 2.0 (Folsom)CC: apevec, jkt, markmc, nobody
Target Milestone: beta   
Target Release: 3.0   
Hardware: All   
OS: Linux   
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Fixed In Version: Doc Type: Bug Fix
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Last Closed: 2013-05-22 18:24:30 UTC Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Embargoed:

Description Perry Myers 2012-12-25 15:52:35 UTC
This could be possible by utilizing the Alembic library

Comment 1 Alan Pevec 2013-01-10 19:27:00 UTC
upstream post pointing to design summit session:
http://lists.openstack.org/pipermail/openstack-dev/2012-November/003096.html
https://etherpad.openstack.org/nova-backportable-db-migrations

where conclusion seems to was "Alembic didn't make it better, it just had different issues."

Assigning to David since he's working on migration to Alembic upstream.

Comment 2 David Ripton 2013-01-10 19:38:11 UTC
As Alan noted, there is some resistance upstream to switching Nova from sqlalchemy-migrate to Alembic.  If we resolve the politics then I think it's a pretty easy technical change -- I have code that mostly automates converting the migration scripts in https://review.openstack.org/15196

There is a blueprint for backportable db migrations.  https://blueprints.launchpad.net/nova/+spec/backportable-db-migrations  But the current solution is to leave gaps in the linear migrate numbers, rather than to switch to Alembic, which supports more dynamic migration ordering.

Quantum is using Alembic now.  Commit dbf0b22abb5a55e3.  Requires alembic >= 0.4.1.  Fedora 17 currently ships python-alembic 0.3.0

Comment 3 David Ripton 2013-05-22 18:24:30 UTC
This is a WONTFIX for now, as upstream seems satisfied with sqlalchemy-migrate and things seem to work well enough.  If it flares up again in the future we can make a new bug.