Change DateField to DateTimeField to improve indexing efficency

core/migrations/0017_auto_20161220_1626.py

@@ -0,0 +1,19 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('core', '0016_auto_20161212_1922'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='user',
+            name='last_update',
+            field=models.DateTimeField(verbose_name='last update', auto_now=True),
+        ),
+    ]

core/models.py

@@ -106,7 +106,7 @@ class User(AbstractBaseUser):
         ),
     )
     date_joined = models.DateField(_('date joined'), auto_now_add=True)
-    last_update = models.DateField(_('last update'), auto_now=True)
+    last_update = models.DateTimeField(_('last update'), auto_now=True)
     is_superuser = models.BooleanField(
         _('superuser'),
         default=False,