Summary: This tutorial introduces you to MySQL UUID, shows you how to use it as the primary key for a table, and discusses the pros and cons of using it as the primary key.
Introduction to MySQL UUID
UUID stands for Universally Unique IDentifier. UUID is defined based on RFC 4122, “a Universally Unique Identifier (UUID) URN Namespace”.
UUID is designed as a number that is unique globally in space and time. Two UUID values are expected to be distinct, even if they are generated on two independent servers.
In MySQL, a UUID value is a 128-bit number represented as a utf8 string of five hexadecimal numbers in the following format:
aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeeeCode language: SQL (Structured Query Language) (sql)To generate a UUID value, you use the UUID() function as follows:
UUID()Code language: SQL (Structured Query Language) (sql)The UUID() function returns a UUID value in compliance with UUID version 1 described in the RFC 4122.
For example, the following statement uses the UUID() function to generate a UUID value:
SELECT UUID();Output:
+--------------------------------------+
| UUID() |
+--------------------------------------+
| e5f96fc2-a700-11ee-9e18-0a0027000003 |
+--------------------------------------+
1 row in set (0.04 sec)Code language: SQL (Structured Query Language) (sql)MySQL UUID vs. Auto-Increment INT as the primary key
Pros
Using UUID for a primary key has the following advantages:
- UUID values are unique across tables, databases, and even servers that allow you to merge rows from different databases or distribute databases across servers.
- UUID values do not expose the information about your data so they are safer to use in a URL. For example, if a customer with ID 10 accesses his account via
http://www.example.com/customers/10/URL, it is easy to guess that there is a customer 11, 12, etc., and this could be a target for an attack. - UUID values can be generated anywhere which can help avoid a round trip to the database server. It also simplifies logic in the application. For example, to insert data into a parent table and child tables, you have to insert into the parent table first, get the generated ID, and then insert data into the child tables. By using UUID, you can generate the primary key value of the parent table up front and insert rows into both parent and child tables at the same time within a transaction.
Cons
Besides the advantages, UUID values also come with some disadvantages:
- Storing UUID values (16 bytes) takes more storage than integers (4 bytes) or even big integers(8 bytes).
- Debugging seems to be more difficult, imagine the expression
WHERE id = 'df3b7cb7-6a95-11e7-8846-b05adad3f0ae'instead ofWHERE id = 10 - Using UUID values may cause performance issues due to their size and not being ordered.
MySQL UUID solution
In MySQL, you can store UUID values in a compact format (BINARY) and display them in human-readable format (VARCHAR) with the help of the following functions:
UUID_TO_BINBIN_TO_UUIDIS_UUID
Notice that UUID_TO_BIN(), BIN_TO_UUID(), and IS_UUID() functions are only available in MySQL 8.0 or later.
The UUID_TO_BIN() function converts a UUID from a human-readable format (VARCHAR) into a compact format (BINARY) format for storing and the BIN_TO_UUID() function converts UUID from the compact format (BINARY) to human-readable format (VARCHAR) for displaying.
The IS_UUID() function returns 1 if the argument is a valid string-format UUID. If the argument is not valid string format UUID, the IS_UUID function returns 0. In case the argument is NULL, the IS_UUID() function returns NULL.
The following are the valid string-format UUIDs in MySQL:
aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee
aaaaaaaabbbbccccddddeeeeeeeeeeee
{aaaaaaaa-bbbb-cccc-dddd-eeeeeeeeeeee}Code language: SQL (Structured Query Language) (sql)MySQL UUID examples
Let’s take a look at an example of using UUID as the primary key.
1) Basic MySQL UUID example
First, create a new table called customers:
CREATE TABLE customers (
id BINARY(16) PRIMARY KEY,
name VARCHAR(255)
);Code language: SQL (Structured Query Language) (sql)Second, insert UUID values into the id column using the UUID() and UUID_TO_BIN() functions as follows:
INSERT INTO customers(id, name)
VALUES(UUID_TO_BIN(UUID()),'John Doe'),
(UUID_TO_BIN(UUID()),'Will Smith'),
(UUID_TO_BIN(UUID()),'Mary Jane');Code language: SQL (Structured Query Language) (sql)Third, query data from a UUID column and use BIN_TO_UUID() function to convert binary format to human-readable format:
SELECT
BIN_TO_UUID(id) id,
name
FROM
customers; Code language: SQL (Structured Query Language) (sql)Output:
+--------------------------------------+------------+
| id | name |
+--------------------------------------+------------+
| 6ab66253-a701-11ee-9e18-0a0027000003 | John Doe |
| 6ab66917-a701-11ee-9e18-0a0027000003 | Will Smith |
| 6ab66b0e-a701-11ee-9e18-0a0027000003 | Mary Jane |
+--------------------------------------+------------+
3 rows in set (0.01 sec)Code language: JavaScript (javascript)2) Using UUID as the default value for the primary key
First, create a new table called vendors:
CREATE TABLE vendors(
id BINARY(16) DEFAULT (UUID_TO_BIN(UUID())),
name VARCHAR(255),
PRIMARY KEY(id)
);Code language: PHP (php)In the vendors table, we use the result of the expression UUID_TO_BIN(UUID()) as the default value for the primary key column. Therefore, we don’t need to specify the value for the id column whenever we insert a new row into the table.
Second, insert a new row into the vendors table:
INSERT INTO vendors(name)
VALUES('ABC Inc.');Code language: JavaScript (javascript)Third, retrieve data from the vendors:
SELECT
BIN_TO_UUID(id) id,
name
FROM
vendors; Output:
+--------------------------------------+----------+
| id | name |
+--------------------------------------+----------+
| 2c56abc6-a704-11ee-9e18-0a0027000003 | ABC Inc. |
+--------------------------------------+----------+
1 row in set (0.00 sec)Code language: JavaScript (javascript)In this tutorial, you have learned about MySQL UUID and how to use it for the primary key column.
