> > ...and what happens if these methods are called and the tables > > already exist? > > > > What if they exist but don't match the spec that SA has created? > > if you're concerned about people running your application against > databases created from a different version and then failing, I > would suggest adding a "version" table to your database which > contains data corresponding against the version of your application > in some way. There has been interest among some SA users over > building a generic "schema comparison" system and I think even some > prototypes are available, though I think thats a fairly complicated > and unreliable approach to take for this particular issue. > we've put such a notion in our db, so the db knows what model-version it matches. Then, at start, depending on the versions one can decide which migration script to execute (if the db should be made to match the py-model), or which feautures to drop (if py-model should follow the db). btw there should be some tricky strategy as of what to call "db-model-version" and when that "version" really changes.
As of the diff, sooner or later i'll have that really working, the one in dbcook.misc is just a start, to show it is possible. Although it would be only useful to automate to some extent the creation of migration scripts; the rest would still be a manual work. btw there should be some "readonly" way to start such an app (like *nix initial filesystem mounting); last month i run one new app by mistake over some legacy mssql db of completely different app, and it did create _alot_ of things; by chance there was nothing overwriten so noone really caught me (-:. ciao svilen --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~----------~----~----~----~------~----~------~--~---
