[openstack-dev] Promoting healing script to scheme migration script?

Jakub Libosvar libosvar at redhat.com
Mon Jun 9 14:18:06 UTC 2014


Hi all,

I'd like to get some opinions on following idea:

Because currently we have (thanks to Ann) WIP of healing script capable
of changing database scheme by comparing tables in the database to
models in current codebase, I started to think whether it could be used
generally to db upgrades instead of "generating" migration scripts.

If I understand correctly the purpose of migration scripts used to be to:
1) separate changes according plugins
2) upgrade database scheme
3) migrate data according the changed scheme

Since we dropped on conditional migrations, we can cross out no.1).
The healing script is capable of doing no.2) without any manual effort
and without adding migration script.

That means if we will decide to go along with using script for updating
database scheme, migration scripts will be needed only for data
migration (no.3)) which are from my experience rare.

Also other benefit would be that we won't need to store all database
models from Icehouse release which we probably will need in case we want
to "heal" database in order to achieve idempotent Icehouse database
scheme with Juno codebase.

Please share your ideas and reveal potential glitches in the proposal.

Thank you,
Kuba



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