#3623: select_related(depth=n) for low n gives corrupt results
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Reporter: [EMAIL PROTECTED] | Owner: adrian
Status: new | Component: Database wrapper
Version: SVN | Keywords: select_related, depth
Stage: Unreviewed | Has_patch: 0
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Hi,
I've found that in some cases select_related(depth=n) returns different
results from select_related.
Here's a slice of my model:
----
class Lval(models.Model):[[BR]]
var_id = models.IntegerField(null=True, db_index=True)[[BR]]
printed = models.CharField(maxlength=100, core=True)[[BR]]
rep_size = models.IntegerField(null=True)[[BR]]
declared_at = models.ForeignKey(Program_point, null=True)[[BR]]
class Access(models.Model):[[BR]]
lval = models.ForeignKey(Lval, related_name="reads_writes")[[BR]]
accessed_through = models.ForeignKey(Call_path)[[BR]]
occurs_at = models.ForeignKey(Program_point)[[BR]]
locks = models.ManyToManyField(Lval,
filter_interface=models.VERTICAL)[[BR]]
class Race(models.Model):[[BR]]
access1 = models.ForeignKey(Access, core=True,
related_name="racy1")[[BR]]
access2 = models.ForeignKey(Access, core=True,
related_name="racy2")[[BR]]
note = models.ForeignKey(Note, core=True, null=True)[[BR]]
labels = models.ManyToManyField(Label,
filter_interface=models.VERTICAL)[[BR]]
class Race_cluster(models.Model):[[BR]]
races = models.ManyToManyField(Race,
filter_interface=models.VERTICAL)[[BR]]
run = models.ForeignKey(Run)[[BR]]
def program(self):[[BR]]
return str(self.run.code)[[BR]]
def first_race(self):[[BR]]
return str(self.races.all()[0])[[BR]]
----
when i run the following code:
r = Run.objects.get(id=27)[[BR]]
this_run = Race_cluster.objects.filter(run = r)[[BR]]
for rc in this_run:[[BR]]
races = rc.races.select_related()[[BR]]
lval = races[0].access2.lval[[BR]]
print lval.var_id[[BR]]
I get:
320931
324744
365766
440030
426104
282968
19893
45442 ...
(which is fine...)
but if I change it to select_related(depth=2)
I get:
fs/dcache.c
fs/bio.c
fs/proc/generic.c
include/asm/processor.h
mm/slab.c
fs/block_dev.c
net/rxrpc/transport.c
net/ipv4/igmp.c
lib/kobject.c
kernel/auditsc.c
fs/nfs/nfs4state.c ...
which is weird...
depth=3 gives me:
296
297
298
281
301
302
309
310
315
316 ...
which is also different
finally, depth=4 gives
320931
324744
365766
440030
426104
282968
19893
45442 ...
which is the same as an unbounded select_related().
Also, if I change one line from:[[BR]]
lval = races[0].access2.lval[[BR]]
to[[BR]]
lval = races[0].access1.lval[[BR]]
it works fine w/ depth=2, etc.
I'm not sure if it was meant to work with low depths, but it seems like it
should still work. The problem might be some funkyness w/ possibly null
foreign keys in my model? BTW, this is running on top of MySQL. Let me
know if you need more info. Thanks.
Jan Voung
--
Ticket URL: <http://code.djangoproject.com/ticket/3623>
Django Code <http://code.djangoproject.com/>
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