GEN_RANDOM_UUID

Generate a new random UUID (version 4).

Syntax

GEN_RANDOM_UUID()

Description

## Overview Generates a new random UUID conforming to version 4 of RFC 4122. The value is produced from a cryptographically secure random number generator. Use this function in PG-compat SQL that expects `gen_random_uuid()` to be available. GEN_RANDOM_UUID is a PG-compat alias for UUID and UUID_GENERATE_V4. All three return the same format and randomness guarantees. ## Behavior - Non-deterministic: every call returns a different value. - Uses a cryptographically secure random source. - Returns a 36-character lowercase hyphenated string (version 4, variant 10xx). - Never returns NULL. - Side effect free. ## Compatibility - PG-compat alias. Semantically identical to UUID and UUID_GENERATE_V4.

Examples

-- Generate a single UUID
SELECT GEN_RANDOM_UUID();

-- Use as a surrogate primary key
INSERT INTO crm.catalog.contacts (id, name)
VALUES (GEN_RANDOM_UUID(), 'Acme Corp');

-- Stamp a correlation id in a CTE so the same value can be reused
WITH c AS (SELECT GEN_RANDOM_UUID() AS cid) SELECT c.cid FROM c;

-- Generate two distinct values in one SELECT
SELECT GEN_RANDOM_UUID() AS uuid_1, GEN_RANDOM_UUID() AS uuid_2;

-- Validate that a generated UUID passes IS_UUID
SELECT IS_UUID(GEN_RANDOM_UUID());  -- true

Pitfalls

• Non-deterministic: the value changes on every call. Freeze the value in a CTE if you need to reference the same UUID in multiple projections or subqueries.
• UUID v4 values are not time-ordered. Writes in time order do not produce monotonically sorted identifiers, which can hurt B-tree index locality on write-heavy tables.
• The function cannot be evaluated at plan time. Optimizers will not fold `GEN_RANDOM_UUID()` into a literal, even when it appears in a WHERE clause.
• To test for UUID-ness downstream, prefer IS_UUID over regex; IS_UUID accepts both hyphenated and unhyphenated forms consistently.

See Also

• uuid
• uuid_generate_v4
• is_uuid