UUID vs. BIGINT: Choosing the Right Primary Key for Your PostgreSQL Cluster

Should I use UUID or BIGINT as the primary key?

Some say BIGINT is better for performance, while others claim UUID is necessary for distributed systems. But what’s the real answer?

What is BIGINT?

• BIGINT (auto-incremented IDs) are sequential numbers (e.g., 1, 2, 3, …).

• They are easy to use and efficient for indexing.

• PostgreSQL uses a sequence generator to ensure uniqueness.

What is UUID?

• UUID (Universally Unique Identifier) is a random 128-bit string (e.g., 550e8400-e29b-41d4-a716–446655440000).

• It is globally unique without needing a central sequence.

• Useful in distributed systems where multiple databases generate IDs independently.

The BIGINT Myth: Is It Always Safe in PostgreSQL Clusters?

A common misconception is that BIGINT auto-increment is always safe in a PostgreSQL cluster. This is true in some cases but not in all.

✅ If You Have a Single Primary Node with Read Replicas (Standard AWS RDS Setup)

• BIGINT is completely safe because only the primary database generates IDs.

• The replica nodes don’t insert data, so there’s no risk of ID conflicts.