I am trying to add indexes on model fields using Field.db_index
for an app that has migrations. Looking at Django's documentation all I need to do is to set db_index=True
:
class Person(models.Model):
first_name = models.CharField()
last_name = models.CharField(db_index=True)
and then I first tried the new Django's Migration:
./manage.py makemigrations app-name
but Migration does not seem to notice the change and does not add the sql command for creating an index. So I tried django-admin.py
as explained here:
django-admin.py sqlindexes app-name
But that does not print the sql command either and it exits with the following error:
CommandError: App 'app-name' has migrations. Only the sqlmigrate and sqlflush commands can be used when an app has migrations.
OK, I managed to create the indexes using Meta.index_together
. It is not the cleanest way, since I am not actually indexing multiple fields together but it works with makemigrations
:
class Person(models.Model):
class Meta():
index_together = [['last_name']]
first_name = models.CharField()
last_name = models.CharField()
Now makemigrations
does make a new migration:
./manage.py makemigrations app-name
>>Migrations for 'app-name':
>> 0005_auto_20140929_1540.py:
>> - Alter index_together for Person (1 constraint(s))
And the corresponding sql command is actually CREATE INDEX
.
./manage.py sqlmigrate app-name 0005_auto_20140929_1540
>>BEGIN;
>>CREATE INDEX app-name_person_last_name_7...4_idx ON `app-name_person` (`last_name`);
>>COMMIT;