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    AnalyticDB:UUID-OSSP

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    AnalyticDB:UUID-OSSP

    Last Updated:Mar 30, 2026

    The uuid-ossp extension provides functions for generating universally unique identifiers (UUIDs). In distributed systems, UUIDs offer stronger uniqueness guarantees than sequences, making them a reliable choice for primary keys and record identifiers across nodes.

    UUID format

    A UUID consists of 32 hexadecimal digits arranged as five groups separated by hyphens: 8-4-4-4-12. For example:

    a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11

    PostgreSQL accepts UUIDs in several equivalent formats:

    Format

    Example

    Standard (lowercase)

    a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11

    Uppercase

    A0EEBC99-9C0B-4EF8-BB6D-6BB9BD380A11

    Braces

    {a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11}

    No hyphens

    a0eebc999c0b4ef8bb6d6bb9bd380a11

    Hyphens after every 4 digits

    a0ee-bc99-9c0b-4ef8-bb6d-6bb9-bd38-0a11

    Mixed

    {a0eebc99-9c0b4ef8-bb6d6bb9-bd380a11}

    UUID fields cannot be used as the distribution key in AnalyticDB for PostgreSQL.

    Install the extension

    Before generating UUIDs, install the uuid-ossp extension from the Extensions page of your instance. For details, see Install, update, and uninstall extensions.

    UUID generation functions

    Version 1: time-based

    uuid_generate_v1() generates a UUID from the current timestamp and the host machine's MAC address.

    uuid_generate_v1mc() works like uuid_generate_v1() but uses a random multicast MAC address instead of the real MAC address, avoiding direct exposure of the machine's hardware identifier.

    Warning

    Version 1 UUIDs embed the MAC address of the generating machine and include a time component, making them somewhat predictable. Avoid version 1 UUIDs in security-sensitive applications.

    Version 3: name-based (MD5)

    uuid_generate_v3(namespace uuid, name text) generates a deterministic UUID by hashing name within namespace using MD5.

    • namespace: a constant returned by one of the uuid_ns_*() functions (see Namespace constants).

    • name: an identifier within the namespace.

    SELECT uuid_generate_v3(uuid_ns_url(), 'example.com');

    The same inputs always produce the same UUID. No random algorithm or system environment is involved, so the result is fully reproducible.

    Version 4: random

    uuid_generate_v4() generates a UUID based on random numbers.

    Version 5: name-based (SHA-1)

    uuid_generate_v5(namespace uuid, name text) works like uuid_generate_v3() but uses SHA-1 instead of MD5. SHA-1 is more secure than MD5, so prefer version 5 over version 3 whenever you need name-based UUIDs.

    Namespace constants

    Use these constants as the namespace argument in uuid_generate_v3() and uuid_generate_v5().

    Function

    Namespace

    uuid_ns_dns()

    Domain Name System (DNS)

    uuid_ns_url()

    URL

    uuid_ns_oid()

    ISO object identifier (OID) — defined by the Abstract Syntax Notation One (ASN.1) standard; different from PostgreSQL OIDs

    uuid_ns_x500()

    X.500 distinguished name (DN)

    uuid_nil() returns a nil UUID constant, which is not a real UUID.

    Examples

    -- Version 1 (time-based)
SELECT uuid_generate_v1();
     uuid_generate_v1
--------------------------------------
 c7f83ba4-bd93-11e9-8674-40a8f01ec4e8
(1 row)
    -- Version 3 (name-based, MD5)
SELECT uuid_generate_v3(uuid_ns_url(), 'example.com');
     uuid_generate_v3
--------------------------------------
 a0473a67-27a1-3c05-a2d1-5c134639347f
(1 row)
    -- Version 4 (random)
SELECT uuid_generate_v4();
     uuid_generate_v4
--------------------------------------
 d7a8d47e-58e3-4bd9-9340-8553ac03d144
(1 row)
    -- Version 5 (name-based, SHA-1)
SELECT uuid_generate_v5(uuid_ns_url(), 'example.com');
     uuid_generate_v5
--------------------------------------
 a5cf6e8e-4cfa-5f31-a804-6de6d1245e26
(1 row)

    References