![]() Using CHAR(36) simplifies this example, but see " Making UUIDs More Performant in MySQL" for why you don't want to use strings for performance reasons. Here's an example where a table users uses UUIDs for its primary key. ![]() RANDOM_BYTES() was introduced in MySQL v5.6.17 (2014), and is currently not available in MariaDB. This uses RANDOM_BYTES() instead of RAND() because the former is non-deterministic and therefore more cryptographically secure, resulting in fewer UUID collisions in the end. Note that UUIDs of this kind reveal the identity of the computer that created the identifier and the time at which it did so, which might make it unsuitable for certain security-sensitive applications. '-', HEX( FLOOR(ASCII(RANDOM_BYTES( 1)) / 64) + 8), SUBSTR(HEX(RANDOM_BYTES( 2)), 2, 3), UUID v4 is a random UUID, meaning it is generated using random bytes instead of a timestamp or other data. This involves the MAC address of the computer and a time stamp. RETURN LOWER(CONCAT( '-', '-', '-', '-', a version without variables, to remove any overhead they might add: CREATE FUNCTION uuid_v4() RETURNS CHAR( 36) ![]() 1st group is 12 characters = 6 bytes SET = HEX(RANDOM_BYTES( 6)) 4th group is 4 characters = 2 bytes, starting with a: 8, 9, A, or B SET = CONCAT(HEX( FLOOR(ASCII(RANDOM_BYTES( 1)) / 64) + 8), SUBSTR(HEX(RANDOM_BYTES( 2)), 2, 3)) import uuid4 from uuid4 // Generate a new UUID var id uuid4. uuidgeneratev4() uses arc4random to determine the random part. 3rd group is 4 characters = 2 bytes, starting with a: 4 SET = CONCAT( '4', SUBSTR(HEX(RANDOM_BYTES( 2)), 2, 3)) A Node.js module for generating and validation V4 UUIDs. As in other UUIDs, 4 bits are used to indicate version 4, and 2 or 3 bits to indicate the. 2nd group is 4 characters = 2 bytes SET = HEX(RANDOM_BYTES( 2)) Here's the function, with comments explaining each group: CREATE FUNCTION uuid_v4() RETURNS CHAR( 36)īEGIN - 1st group is 8 characters = 4 bytes SET = HEX(RANDOM_BYTES( 4)) Universally unique identifiers (UUIDs) are 128-bit (16-byte) numbers that are designed to be globally unique, and as a result they make for great primary keys. Why You Should Use UUIDs for Your Primary Keys
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