title: Migration of Django field with default value 0 to PostgreSQL database
body: <p>I want to update default column value but it seems like default value on columns is  is only on the ORM layer, and is not actually setting a default value in the DB and returns error django.db.utils.OperationalError: cannot ALTER TABLE "bps_registration_application" because it has pending trigger events.     Is it possible to  update default columnn value to 0 in postgress migrations by updating in django model?</p>
  
  <p>This is models.py.        </p>
  
  <pre><code>class Application(models.Model):
      registration_date = models.CharField(max_length=15)
      building_use = models.ForeignKey(to=system_settings.models.BuildingUse)
      building_category = models.CharField(max_length=30)
      building_structure_category = models.ForeignKey(to=system_settings.models.BuildingStructureCategory)
      building_length_ft = models.IntegerField(blank=True,  default=0)
      building_breadth_ft = models.IntegerField(blank=True,  default=0)
      building_height_ft = models.IntegerField(blank=True, default=0)
      building_length_in = models.IntegerField(blank=True,  default=0)
      building_breadth_in = models.IntegerField(blank=True,  default=0)
      building_height_in = models.IntegerField(blank=True,  default=0)
  
      building_storey = models.IntegerField(blank=True,  default=0)
      building_area = models.DecimalField(max_digits=6, decimal_places=2)
  
      reg = models.ForeignKey(NewRegistration)
  </code></pre>