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):
var_id = models.IntegerField?(null=True, db_index=True)
printed = models.CharField?(maxlength=100, core=True)
rep_size = models.IntegerField?(null=True)
declared_at = models.ForeignKey?(Program_point, null=True)
class Access(models.Model):
lval = models.ForeignKey?(Lval, related_name="reads_writes")
accessed_through = models.ForeignKey?(Call_path)
occurs_at = models.ForeignKey?(Program_point)
locks = models.ManyToManyField?(Lval, filter_interface=models.VERTICAL)
class Race(models.Model):
access1 = models.ForeignKey?(Access, core=True, related_name="racy1")
access2 = models.ForeignKey?(Access, core=True, related_name="racy2")
note = models.ForeignKey?(Note, core=True, null=True)
labels = models.ManyToManyField?(Label, filter_interface=models.VERTICAL)
class Race_cluster(models.Model):
races = models.ManyToManyField?(Race, filter_interface=models.VERTICAL)
run = models.ForeignKey?(Run)
def program(self):
return str(self.run.code)
def first_race(self):
return str(self.races.all()[0])
when i run the following code:
r = Run.objects.get(id=27)
this_run = Race_cluster.objects.filter(run = r)
for rc in this_run:
races = rc.races.select_related()
lval = races[0].access2.lval
print lval.var_id
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:
lval = races[0].access2.lval
to
lval = races[0].access1.lval
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
