---
id: 'uuid-ossp'
title: 'uuid-ossp: Unique Identifiers'
description: 'A UUID generator for PostgreSQL.'
---

The `uuid-ossp` extension can be used to generate a `UUID`.

## Overview

A `UUID` is a "Universally Unique Identifier" and it is, for practical purposes, unique.
This makes them particularly well suited as Primary Keys. It is occasionally referred to as a `GUID`, which stands for "Globally Unique Identifier".

## Enable the extension

**Note**:
Currently `uuid-ossp` extension is enabled by default and cannot be disabled.

<Tabs
  scrollable
  size="small"
  type="underlined"
  defaultActiveId="dashboard"
  queryGroup="database-method"
>
<TabPanel id="dashboard" label="Dashboard">

1. Go to the [Database](/dashboard/project/_/database/tables) page in the Dashboard.
2. Click on **Extensions** in the sidebar.
3. Search for `uuid-ossp` and enable the extension.

</TabPanel>
<TabPanel id="sql" label="SQL">

```sql
-- Example: enable the "uuid-ossp" extension
create extension "uuid-ossp" with schema extensions;

-- Example: disable the "uuid-ossp" extension
drop extension if exists "uuid-ossp";
```

Even though the SQL code is `create extension`, this is the equivalent of "enabling the extension".
To disable an extension, call `drop extension`.

It's good practice to create the extension within a separate schema (like `extensions`) to keep the `public` schema clean.

**Note**:
Currently `uuid-ossp` extension is enabled by default and cannot be disabled.

</TabPanel>
</Tabs>

## The `uuid` type

Once the extension is enabled, you now have access to a `uuid` type.

## `uuid_generate_v1()`

Creates a UUID value based on the combination of computer’s MAC address, current timestamp, and a random value.

<Admonition type="note">

UUIDv1 leaks identifiable details, which might make it unsuitable for certain security-sensitive applications.

</Admonition>

## `uuid_generate_v4()`

Creates UUID values based solely on random numbers. You can also use Postgres's built-in [`gen_random_uuid()`](https://www.postgresql.org/docs/current/functions-uuid.html) function to generate a UUIDv4.

## Examples

### Within a query

```sql
select uuid_generate_v4();
```

### As a primary key

Automatically create a unique, random ID in a table:

```sql
create table contacts (
  id uuid default uuid_generate_v4(),
  first_name text,
  last_name text,
  primary key (id)
);
```

## Resources

- [Choosing a Postgres Primary Key](/blog/choosing-a-postgres-primary-key)
- [The Basics Of Postgres `UUID` Data Type](https://www.pgtutorial.com/postgresql-tutorial/postgresql-uuid/)
