Why to use Django BigAutoField Explained in simplified way

🔹 What is BigAutoField?

BigAutoField is a primary key field type in Django. It’s like an AutoField, but it uses a 64-bit integer instead of a 32-bit integer. That means it can hold much larger values.

In databases:

• AutoField → usually maps to INT (32-bit, max ≈ 2.1 billion)
• BigAutoField → maps to BIGINT (64-bit, max ≈ 9.2 quintillion)

🔹 Why Django Introduced It

Large applications can have billions of rows. A normal AutoField (32-bit) runs out of IDs at ≈ 2.1 billion. BigAutoField solves this by allowing much larger primary key ranges.

🔹 Example Usage

You can explicitly define it in a model:

id = models.BigAutoField(primary_key=True)

Or globally in your project (Django 3.2+ default):

DEFAULT_AUTO_FIELD = "django.db.models.BigAutoField"

This means: If you don’t explicitly define a primary key, Django will use BigAutoField automatically.

🔹 When to Use It

• ✅ Use BigAutoField if:
  • Your app will store billions of rows (e.g., logs, transactions, analytics).
  • You want to future-proof your schema.
• ❌ You can stick with AutoField if:
  • Your tables will never reach billions of rows.
  • You want smaller DB index sizes (slightly more efficient).

🔹 Difference Between AutoField vs BigAutoField

Field	DB Type	Range	Default in Django
AutoField	INT	-2,147,483,648 to 2,147,483,647	Before Django 3.2
BigAutoField	BIGINT	-9,223,372,036,854,775,808 to 9,223,372,036,854,775,807	Django 3.2+

✅ In Short

BigAutoField is just a bigger auto-incrementing primary key. Django switched to it as the default in Django 3.2 to avoid hitting ID limits for big projects.

from django.db import models

class MyModel(models.Model):
    id = models.BigAutoField(primary_key=True)
    name = models.CharField(max_length=100)
  

References

Django BigAutoField official documentation