> -----Original Message----- > From: sqlalchemy@googlegroups.com > [mailto:[EMAIL PROTECTED] On Behalf Of Chris Withers > Sent: 13 February 2008 13:51 > To: sqlalchemy@googlegroups.com > Subject: [sqlalchemy] Re: schema changes > > > Michael Bayer wrote: > > > >> What if they exist but don't match the spec that SA has created? > > > > just try it out...create_all() by default checks the system > tables for > > the presence of a table first before attempting to create it > > Cool, > > > (same > > with dropping). > > When would SA drop a table?
When you ask it to via metadata.drop_all() or table.drop(). Docs are here: http://www.sqlalchemy.org/docs/04/metadata.html#metadata_creating > > > this is controlled by a flag called "checkfirst". > > This a parameter to the methods or does it need to be set in > some config > file? > See the docs referenced above. SQLAlchemy on its own doesn't use config files, but some of the frameworks that use it (eg. TurboGears and pylons) allow some SQLAlchemy-related configuration to be done in config files. > > 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. > > Good plan. > > > 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. > > Do the projects have a name? > I don't know about generic comparisons, but the Migrate project might be a place to start: http://code.google.com/p/sqlalchemy-migrate/ (Note that it is only in the process of being updated for SA 0.4) Hope that helps, Simon --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
