What you are talking about here is somewhat covered in http://code.djangoproject.com/ticket/6148 But here it is called db_schema instead.
In mysql "schema" is aliased to database. In postgres, (and probably oracle) it actually is a different schema within the same database. I made some work on that ticket up to about rel 1.0 and I am currently using it for solving the one database per app use case. I just create a base model in my app that defines db_schema and let all other app models inherit from that one. It's not a perfect solution but works for me. //Peter p.s. I would really like someone to continue the development of that ticket since I have been moved to other projects and don't have the time for it any more. On Sep 13, 12:18 am, Simon Willison <[EMAIL PROTECTED]> wrote: > On Sep 12, 7:45 pm, Brent Hagany <[EMAIL PROTECTED]> wrote: > > > As far as I can tell, the argument about being portable is a good one, > > and if that ends up being the reason this doesn't get in right away, > > then I can't complain. However, the part about the single server > > making this more specialized, and the part about performance are non > > sequiturs. The vast majority of web applications run with a single > > database server; I don't see how that can be called specialized. And, > > the reasons for wanting to do cross-database joins (from my POV) have > > nothing to do with performance, so I don't really understand why it's > > relevant to this part of the proposal. > > To be honest, the main reason I proposed avoiding this problem is it > sounded like it might be difficult so I was trying to constrain the > scope a bit, plus I don't know if the ability to do cross-database > joins exists outside of MySQL. From a quick search, it looks like > PostgreSQL doesn't support it:http://www.postgresql.org/docs/faqs.FAQ.html > but Oracle does:http://www.remote-dba.cc/oracle_tips_sql_joins.htm > > Anyway, it turns out Django supports cross-database joins in MySQL > already! It's a bit of a hack, but it works right now, with no > modifications needed to Django at all. > > The only difference between a cross-database join and a regular join > in MySQL is that in cross-database joins the database name is included > in each table reference: > > SELECT database1.table1.column1, database2.table2.column2 > FROM database1.table1 ... > > So, my first attempt was to add the database name to the db_table > property in class Meta: > > class Topic(models.Model): > name = models.CharField(max_length = 100) > slug = models.SlugField() > > class Meta: > db_table = "other_database.review_topic" > > def __unicode__(self): > return self.name > > That didn't work, because Django adds escaping quotes around each > table reference. Here's the generated SQL: > > SELECT > `other_database. review_topic `.`id`, > `other_database.review_topic`.`name`, > `other_database.review_topic`.`slug` > FROM `other_database.review_topic` > > You can probably guess where this is going: if you include the > backticks around the . in your db_table setting everything works just > fine! > > class Meta: > db_table = "other_database`.`review_topic" > > Regular selects, joins and everything else appear to Just Work out of > the box. It turns out we don't have to do anything special to enable > cross-database joins / models in different databases accessible > through the same logical connection on MySQL, which is pretty cool. > It's a shame the syntax is hacky though. One slight improvement would > be to allow the db_table property to optionally include its own table > quoting and only add backticks if that string didn't have them > already. That way you could do the following, which is slightly less > hacky: > > class Meta: > db_table = "`other_database`.`review_topic`" > > Cheers, > > Simon --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Django developers" group. To post to this group, send email to django-developers@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/django-developers?hl=en -~----------~----~----~----~------~----~------~--~---
