Should I use ArrayField or ManyToManyField for tags

I am trying to add tags to a model for a postgres db in django and I found two solutions:

using foreign keys:

class Post(models.Model):
    tags = models.ManyToManyField('tags')
    ...

class Tag(models.Model):
    name = models.CharField(max_length=140)

using array field:

from django.contrib.postgres.fields import ArrayField

class Post(models.Model):
    tags = ArrayField(models.CharField(max_length=140))
    ...

assuming that I don't care about supporting other database-backends in my code, what is a recommended solution ?

If you use an Array field,

• The size of each row in your DB is going to be a bit large thus Postgres is going to be using more toast tables

• Every time you get the row, unless you specifically use defer the field or otherwise exclude it from the query via only, or values or something, you paying the cost of loading all those values every time you iterate across that row. If that's what you need then so be it.

• Filtering based on values in that array, while possible isn't going to be as nice and the Django ORM doesn't make it as obvious as it does for M2M tables.

If you use M2M field,

• You can filter more easily on those related values Those fields are postponed by default, you can use prefetch_related if you need them and then get fancy if you want only a subset of those values loaded.

• Total storage in the DB is going to be slightly higher with M2M because of keys, and extra id fields.

• The cost of the joins in this case is completely negligible because of keys.

With that being said, the above answer doesn't belong to me. A while ago, I had stumbled upon this dilemma when I was learning Django. I had found the answer here in this question, Django Postgres ArrayField vs One-to-Many relationship.

Hope you get what you were looking for.