django Charfield suitable for a primary key?
<p>In my django model I would like to set the field <code>unique_id</code> below to be the primary key as this will be the field used in queries for the model.  It satisfies <code>unique=True</code> and <code>null=False</code>. However as django sets an AutoField to primary key in the background I'm unsure whether a CharField (which uses a unique 3 character code) is suitable as a primary key or whether this will be sub-optimal?</p>

<pre><code>class PaymentMethod(models.Model):
    unique_id = models.CharField(max_length=3)
    last_updated = models.DateTimeField(auto_now=True)
</code></pre>