How Can I Replace Django\'s Auto-Incrementing Primary Key with a Unique, Short, Integer ID?

Replacing Django's Primary Key with a Unique Integer

Problem Outline

In Django, the default primary key is an auto-incremented positive integer used throughout the application. However, this publicly exposes the number of entities in the database, prompting the need for an alternative. This article addresses a specific set of requirements for an obfuscated primary key:

• Integer data type
• Avoidance of hashing/unhashing for every read/write/comparison
• One-time hashing at record insertion
• Unique hashed value within a specific table
• Minimal length for short URLs

Proposed Solution

Instagram's method, inspired by this article, meets these requirements. The generated ID consists of:

• 41 bits for a time-based component
• 23 bits chosen at random

Code Implementation

ID Generation:

START_TIME = <unix timestamp>

def make_id():
    t = int(time.time()*1000) - START_TIME
    u = random.SystemRandom().getrandbits(23)
    id = (t << 23) | u
    return id

def reverse_id(id):
    t = id >> 23
    return t + START_TIME

Model:

class MyClass(models.Model):
    id = models.BigIntegerField(default=fields.make_id, primary_key=True)

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