What is bigserial in PostgreSQL: Explanation and Usage

bigserial in PostgreSQL is a special data type used to create auto-incrementing 64-bit integer columns. It automatically generates unique large integer values for new rows, often used for primary keys when you expect many records.

How It Works

Think of bigserial as a counter that automatically increases by one each time you add a new row to a table. It uses a hidden sequence behind the scenes to keep track of the last number used. When you insert a new row without specifying a value for the bigserial column, PostgreSQL fetches the next number from this sequence and assigns it.

This is like a ticket dispenser at a deli: each customer gets a unique number in order, so no two customers have the same ticket. The difference is that bigserial uses a 64-bit integer, which means it can count very high—up to about 9 quintillion—so it’s great for tables that might grow very large.

Example

This example shows how to create a table with a bigserial column and insert rows without specifying the ID. PostgreSQL will assign IDs automatically.

sql

CREATE TABLE users (
  id bigserial PRIMARY KEY,
  name text NOT NULL
);

INSERT INTO users (name) VALUES ('Alice');
INSERT INTO users (name) VALUES ('Bob');

SELECT * FROM users;

Output

 id | name 
----+-------
  1 | Alice
  2 | Bob
(2 rows)

When to Use

Use bigserial when you need a unique identifier for rows and expect the table to hold a very large number of records—more than what a regular serial (32-bit) can handle. It is ideal for systems like large user databases, logs, or any application where IDs might exceed 2 billion.

For smaller tables, serial is enough, but bigserial future-proofs your design by allowing much larger values without manual intervention.

Key Points

• bigserial is an auto-incrementing 64-bit integer type.
• It uses a hidden sequence to generate unique values automatically.
• Commonly used for primary keys in very large tables.
• Automatically increments on each new row insert if no value is provided.
• Helps avoid manual ID management and collisions.

Key Takeaways

bigserial automatically generates unique 64-bit integer IDs for new rows.

It is best for tables expected to grow beyond 2 billion rows.

Behind the scenes, it uses a sequence to keep track of the next ID.

Use bigserial to avoid manual ID assignment and ensure uniqueness.

For smaller tables, serial may be sufficient.