I'm having trouble working with multi-db using mysql replication. When
I run our test suite, I'm getting several hundred errors if I have more
than one database configured, and none if I have only one configured.
It seems that something isn't getting properly cleared out between test
cases, so duplicate objects are getting created.
My DATABASES setting looks like this:
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.mysql',
'HOST': 'jellyroll',
'NAME': 'ee',
'USER': 'ee',
'PASSWORD': 'ee',
'OPTIONS': {
'init_command': 'SET storage_engine=INNODB',
'charset' : 'utf8',
'use_unicode' : True,
},
},
'replicant0': {
'ENGINE': 'django.db.backends.mysql',
'HOST': 'jellyroll-rep0',
'NAME': 'test',
'USER': 'ee',
'PASSWORD': 'ee',
'TEST_MIRROR': 'default',
'OPTIONS': {
'init_command': 'SET storage_engine=INNODB',
'charset' : 'utf8',
'use_unicode' : True,
},
},
}
My router looks like this:
class PrimaryReplicantRouter(object):
"""Set up routing with one primary database, and zero or more
replicant databases."""
db_list = settings.DATABASES.keys()
primary_db = 'default'
replicant_db_list = [x for x in db_list if x != primary_db]
def db_for_read(self, model, **hints):
try:
return random.choice(self.replicant_db_list)
except IndexError:
return self.primary_db
def db_for_write(self, model, **hints):
"""Write to the Primary DB"""
return self.primary_db
def allow_relation(self, obj1, obj2, **hints):
"""Allow a relationship between any two objects in the db
pool"""
if (obj1._state.db in self.db_list
and obj2._state.db in self.db_list):
return True
return None
def allow_syncdb(self, db, models):
"""All writes go to the primary db."""
return db == self.primary_db
The first error that comes out of the test suite is a duplicate username
in auth during a testcase's setUp, which makes it look like the object
is getting created on one test pass, and then created again the next
time around without deleting it properly:
$ ./manage.py test --failfast
.....E
======================================================================
ERROR: Regressiontest for #12462
----------------------------------------------------------------------
Traceback (most recent call last):
File
"/home/cliff/projects/lr-mdb/lexilereader/web/../contrib/django/contrib/auth/tests/auth_backends.py",
line 14, in setUp
User.objects.create_user('test', 't...@example.com', 'test')
...
IntegrityError: (1062, "Duplicate entry 'test' for key 2")
Any ideas what's going wrong?
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