id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
13946	Database caching doesn't account for multiple databases	tiemonster	nobody	"Database caching doesn't account for multiple databases. As such, when running unit tests, it attempts to create the cache table twice on the default database connection, causing a unit test failure.

Two database connections were defined: default and datastore. CACHE_BACKEND = ""db://cache_table"" Error was as follows:

{{{
Traceback (most recent call last):
  File ""./manage.py"", line 11, in <module>
    execute_manager(settings)
  File ""/usr/local/lib/python2.6/dist-packages/Django-1.2.1-py2.6.egg/
django/core/management/__init__.py"", line 438, in execute_manager
    utility.execute()
  File ""/usr/local/lib/python2.6/dist-packages/Django-1.2.1-py2.6.egg/
django/core/management/__init__.py"", line 379, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File ""/usr/local/lib/python2.6/dist-packages/Django-1.2.1-py2.6.egg/
django/core/management/base.py"", line 191, in run_from_argv
    self.execute(*args, **options.__dict__)
  File ""/usr/local/lib/python2.6/dist-packages/Django-1.2.1-py2.6.egg/
django/core/management/base.py"", line 218, in execute
    output = self.handle(*args, **options)
  File ""/usr/local/lib/python2.6/dist-packages/Django-1.2.1-py2.6.egg/
django/core/management/commands/test.py"", line 37, in handle
    failures = test_runner.run_tests(test_labels)
  File ""/usr/local/lib/python2.6/dist-packages/Django-1.2.1-py2.6.egg/
django/test/simple.py"", line 313, in run_tests
    old_config = self.setup_databases()
  File ""/usr/local/lib/python2.6/dist-packages/Django-1.2.1-py2.6.egg/
django/test/simple.py"", line 270, in setup_databases
    connection.creation.create_test_db(self.verbosity, autoclobber=not
self.interactive)
  File ""/usr/local/lib/python2.6/dist-packages/Django-1.2.1-py2.6.egg/
django/db/backends/creation.py"", line 358, in create_test_db
    call_command('createcachetable', cache_name)
  File ""/usr/local/lib/python2.6/dist-packages/Django-1.2.1-py2.6.egg/
django/core/management/__init__.py"", line 166, in call_command
    return klass.execute(*args, **defaults)
  File ""/usr/local/lib/python2.6/dist-packages/Django-1.2.1-py2.6.egg/
django/core/management/base.py"", line 218, in execute
    output = self.handle(*args, **options)
  File ""/usr/local/lib/python2.6/dist-packages/Django-1.2.1-py2.6.egg/
django/core/management/base.py"", line 318, in handle
    label_output = self.handle_label(label, **options)
  File ""/usr/local/lib/python2.6/dist-packages/Django-1.2.1-py2.6.egg/
django/core/management/commands/createcachetable.py"", line 50, in
handle_label
    curs.execute(""\n"".join(full_statement))
  File ""/usr/local/lib/python2.6/dist-packages/Django-1.2.1-py2.6.egg/
django/db/backends/mysql/base.py"", line 86, in execute
    return self.cursor.execute(query, args)
  File ""/usr/lib/pymodules/python2.6/MySQLdb/cursors.py"", line 166, in
execute
    self.errorhandler(self, exc, value)
  File ""/usr/lib/pymodules/python2.6/MySQLdb/connections.py"", line 35,
in defaulterrorhandler
    raise errorclass, errorvalue
_mysql_exceptions.OperationalError: (1050, ""Table 'cache_table'
already exists"") 
}}}

In my situation, our datastore was a read-only connection. I told Django to treat it as a replication slave using the TEST_MIRROR setting, and the error went away. This won't work for all setups, however. For more information, see discussion on django-users [http://groups.google.com/group/django-users/browse_thread/thread/d2ca91cee6399250/4b133dde16d592f1?show_docid=4b133dde16d592f1 here]."		closed	Core (Cache system)	1.2		fixed	multidb database caching		Accepted	0	0	0	0	0	0