CREATE EXTENSION "uuid-ossp";
SELECT uuid_nil();
               uuid_nil               
--------------------------------------
 00000000-0000-0000-0000-000000000000
(1 row)

SELECT uuid_ns_dns();
             uuid_ns_dns              
--------------------------------------
 6ba7b810-9dad-11d1-80b4-00c04fd430c8
(1 row)

SELECT uuid_ns_url();
             uuid_ns_url              
--------------------------------------
 6ba7b811-9dad-11d1-80b4-00c04fd430c8
(1 row)

SELECT uuid_ns_oid();
             uuid_ns_oid              
--------------------------------------
 6ba7b812-9dad-11d1-80b4-00c04fd430c8
(1 row)

SELECT uuid_ns_x500();
             uuid_ns_x500             
--------------------------------------
 6ba7b814-9dad-11d1-80b4-00c04fd430c8
(1 row)

-- some quick and dirty field extraction functions
-- this is actually timestamp concatenated with clock sequence, per RFC 4122
CREATE FUNCTION uuid_timestamp_bits(uuid) RETURNS varbit AS
$$ SELECT ('x' || substr($1::text, 15, 4) || substr($1::text, 10, 4) ||
           substr($1::text, 1, 8) || substr($1::text, 20, 4))::bit(80)
          & x'0FFFFFFFFFFFFFFF3FFF' $$
LANGUAGE SQL STRICT IMMUTABLE;
CREATE FUNCTION uuid_version_bits(uuid) RETURNS varbit AS
$$ SELECT ('x' || substr($1::text, 15, 2))::bit(8) & '11110000' $$
LANGUAGE SQL STRICT IMMUTABLE;
CREATE FUNCTION uuid_reserved_bits(uuid) RETURNS varbit AS
$$ SELECT ('x' || substr($1::text, 20, 2))::bit(8) & '11000000' $$
LANGUAGE SQL STRICT IMMUTABLE;
CREATE FUNCTION uuid_multicast_bits(uuid) RETURNS varbit AS
$$ SELECT ('x' || substr($1::text, 25, 2))::bit(8) & '00000011' $$
LANGUAGE SQL STRICT IMMUTABLE;
CREATE FUNCTION uuid_node(uuid) RETURNS text AS
$$ SELECT substr($1::text, 25) $$
LANGUAGE SQL STRICT IMMUTABLE;
SELECT uuid_version_bits(uuid_generate_v1()),
       uuid_reserved_bits(uuid_generate_v1()),
       uuid_multicast_bits(uuid_generate_v1());
 uuid_version_bits | uuid_reserved_bits | uuid_multicast_bits 
-------------------+--------------------+---------------------
 00010000          | 10000000           | 00000000
(1 row)

SELECT uuid_version_bits(uuid_generate_v1mc()),
       uuid_reserved_bits(uuid_generate_v1mc()),
       uuid_multicast_bits(uuid_generate_v1mc());
 uuid_version_bits | uuid_reserved_bits | uuid_multicast_bits 
-------------------+--------------------+---------------------
 00010000          | 10000000           | 00000011
(1 row)

-- timestamp+clock sequence should be monotonic increasing in v1
SELECT uuid_timestamp_bits(uuid_generate_v1()) < uuid_timestamp_bits(uuid_generate_v1());
 ?column? 
----------
 t
(1 row)

SELECT uuid_timestamp_bits(uuid_generate_v1mc()) < uuid_timestamp_bits(uuid_generate_v1mc());
 ?column? 
----------
 t
(1 row)

-- node should be stable in v1, but not v1mc
SELECT uuid_node(uuid_generate_v1()) = uuid_node(uuid_generate_v1());
 ?column? 
----------
 t
(1 row)

SELECT uuid_node(uuid_generate_v1()) <> uuid_node(uuid_generate_v1mc());
 ?column? 
----------
 t
(1 row)

SELECT uuid_node(uuid_generate_v1mc()) <> uuid_node(uuid_generate_v1mc());
 ?column? 
----------
 t
(1 row)

SELECT uuid_generate_v3(uuid_ns_dns(), 'www.widgets.com');
           uuid_generate_v3           
--------------------------------------
 3d813cbb-47fb-32ba-91df-831e1593ac29
(1 row)

SELECT uuid_generate_v5(uuid_ns_dns(), 'www.widgets.com');
           uuid_generate_v5           
--------------------------------------
 21f7f8de-8051-5b89-8680-0195ef798b6a
(1 row)

SELECT uuid_version_bits(uuid_generate_v4()),
       uuid_reserved_bits(uuid_generate_v4());
 uuid_version_bits | uuid_reserved_bits 
-------------------+--------------------
 01000000          | 10000000
(1 row)

SELECT uuid_generate_v4() <> uuid_generate_v4();
 ?column? 
----------
 t
(1 row)