Eric Florenzano's Blog - Latest Comments in Easy Multi-Database Support for Django

Re: Easy Multi-Database Support for Django

radyo dinle — Fri, 17 Jul 2009 10:18:00 -0000

that's a great post, thank you!

Re: Easy Multi-Database Support for Django

sohbet — Fri, 17 Jul 2009 10:18:00 -0000

that's a great post, thank you!

Re: Easy Multi-Database Support for Django

DNKorolkov — Thu, 16 Jul 2009 23:15:00 -0000

Of course, different classes must be created for different database:

MultiDBManager_primary = type('MultiDBManager_primary', (MultiDBManager,), {'database':'primary'})

MultiDBManager_secondary = type('MultiDBManager_secondary', (MultiDBManager,), {'database':'secondary'})

Re: Easy Multi-Database Support for Django

DNKorolkov — Thu, 16 Jul 2009 23:05:00 -0000

Problem with create of MultiDBManager for ManyToManyField.

MultiDBManager.__init__ require 'database' parameter.
Its cause error with call "super(ManyRelatedManager, self).__init__()" in ManyRelatedManager.__init__
(function create_many_related_manager of django/db/models/fields/related.py).

Proposed solution:
Set 'database' as class attribute instead __init__ argument:

MultiDBManager = type('MultiDBManager', (MultiDBManager,), {'database':'db_name'})

P.S. Excuse my English, please ;-).

Re: Easy Multi-Database Support for Django

ha22109 — Thu, 16 Jul 2009 19:02:00 -0000

It is throwing an error when i changed my settings.py

the error is:

could not connect to server: No such file or directory
Is the server running locally and accepting
connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?

Re: Easy Multi-Database Support for Django

Emily — Tue, 14 Jul 2009 05:08:00 -0000

If anyone else was stuck with the multiple mysql connections issue, I *think* I have got around it (with help from other people's ideas!):

http://groups.google.com/gr...

Re: Easy Multi-Database Support for Django

Emily — Mon, 06 Jul 2009 21:50:00 -0000

Thanks for this.

I am having issues with multiple connections not being closed though (has been mentioned above).

Has anyone got a work around for this?

Re: Easy Multi-Database Support for Django

Nigel Cohen — Tue, 02 Jun 2009 02:00:00 -0000

I spent many years trying to create multiple databases with MySQL. I finally got to the simple solution (for the several transactional based database applications we wrote) of preceding the table name with the database name (eg. db1.person inner join db2.organisation).

Could this essential (for large apps) multi-database functionality not be achieved quite simply by setting up a variable in the Model object allowing a database name to be updated - which the MySQL generating code looks at when generating the MySQL code?

Re: Easy Multi-Database Support for Django

ben 10 oyunları — Sun, 24 May 2009 21:06:00 -0000

Based on rules written in Lua, you could direct queries using the primary / secondary model you have in this post, or split reads to a Slave instance and writes to a Master.

Re: Easy Multi-Database Support for Django

Richard McMillan — Mon, 11 May 2009 06:25:00 -0000

For those on SVN django: as of 10059 you will need to add :

use_for_related_fields = True

to the subclassed manager for this to work.

Re: Easy Multi-Database Support for Django

Praveen — Thu, 02 Apr 2009 18:23:00 -0000

Hi Nice articles, i have not tried but may be in future will really help.

Re: Easy Multi-Database Support for Django

Mon, 30 Mar 2009 22:19:00 -0000

FYI:

Using _default_manager in a model causes many idle MySQL connections. (Django 1.0)

http://groups.google.com/group/django-users/browse_thread/thread/6ed797f6b00dca90

Re: Easy Multi-Database Support for Django

Jordan Keyes — Mon, 16 Mar 2009 07:15:00 -0000

I may have solved my own problem. In your example I changed the line
"_default_manager = MultiDBManagr('secondary')" to
"objects = MultiDBManager('secondary')" on each model (changing secondary to the appropriate DB name from the Dict.) and things seem to be working appropriately now. The multi_syncdb is still a little borked, but I can do without that.

Thanks for the great tutorial, Eric!

Re: Easy Multi-Database Support for Django

Jordan Keyes — Mon, 16 Mar 2009 04:02:00 -0000

I have tried this both with Django 1.0.2 and with the latest SVN version (from 3/16/09) using the settings Adrian mentioned. Both ways, the multi_syncdb shown seems to be doing a two-way sync (putting all of my models in both databases).
If I run "python manage.py shell" I can manually create items in the tables, but it doesn't appear to be using the _default_manager to decide where to put the items, just going for the secondary database.
Also, it seems the manager is working, but only partially. Any time I try to access the objects in the tables, I get errors like "type object 'TwebprPress' has no attribute 'objects'" (for TwebprPress.objects.all()) Have I done something wrong?

For reference, I am using Python 2.5, Django from SVN, django-mssql from SVN for SQL 2005 connection.

Re: Easy Multi-Database Support for Django

Joseph Kocherhans — Tue, 10 Mar 2009 17:56:00 -0000

As of http://code.djangoproject.c..., this code snippet will no longer work. Fortunately, it's a lot easier/cleaner now. The get_db_wrapper() method can be rewritten something like this (untested):

def get_db_wrapper(self):
database = settings.DATABASES[self.database]
backend = __import__('django.db.backends.' + database['DATABASE_ENGINE']
+ ".base", {}, {}, ['base'])
return backend.DatabaseWrapper(database)

Re: Easy Multi-Database Support for Django

re — Fri, 05 Dec 2008 19:04:00 -0000

good reading!!

Re: Easy Multi-Database Support for Django

jfy3d — Thu, 27 Nov 2008 00:45:00 -0000

Forenkey has error

how fix it ?

Re: Easy Multi-Database Support for Django

guille_ — Sat, 22 Nov 2008 00:48:00 -0000

Not thread-savvy. It would be cool to pass the settings as a dictionary and not changing the global settings object.

Re: Easy Multi-Database Support for Django

enoch — Fri, 21 Nov 2008 06:38:00 -0000

fixed the other problem. type on database name on my part.

looking at a new problem. when i try to access the Link objects i get "type object 'Link" has no attribute 'objects'

l = Link.objects.all()

Re: Easy Multi-Database Support for Django

enoch — Thu, 20 Nov 2008 16:53:00 -0000

looks great. any troubleshooting help. i setup the same stuff and keep getting a problem in the admin views for the Link objects that "Something's wrong with your database installation. Make sure the appropriate database tables have been created, and make sure the database is readable by the appropriate user."

what's odd is, that's on listing, but on "add new" link, it brings up a from fine to add a new link....

Re: Easy Multi-Database Support for Django

Lis — Wed, 19 Nov 2008 21:28:00 -0000

I'm getting deadlocks when trying to update on mysql/innodb
http://dpaste.com/92408/

Re: Easy Multi-Database Support for Django

Leah Culver — Sun, 16 Nov 2008 04:00:00 -0000

That's pretty much how we did things :D Thanks to Malcolm for adding the hooks in Django 1.0 that allow for multiple databases!

Re: Easy Multi-Database Support for Django

Jijnes Patel — Sat, 15 Nov 2008 01:48:00 -0000

Nice post. If you're using MySQL, you could use MySQL Proxy, which will accept connections from your Django application server and inspect the queries. Based on rules written in Lua, you could direct queries using the primary / secondary model you have in this post, or split reads to a Slave instance and writes to a Master.

Re: Easy Multi-Database Support for Django

Atamert Ölçgen — Fri, 14 Nov 2008 22:22:00 -0000

Great post! I don't need sharding for any of my projects. But now I can see how to implement it if needed.

I think it would look much cooler if the database name was a class variable. But I guess it would require patching the models.Manager. Such as;

class MyClass(models.Model):
database = 'secondary'