UUID Type

The data type UUID stores universally unique identifiers (UUID) as defined by RFC 4122, ISO/IEF 9834-8:2005, and related standards. This identifier is a 128-bit quantity that is generated by an algorithm chosen to make it very unlikely that the same identifier will be generated by anyone else in the known universe using the same algorithm.

Therefore, for distributed systems, these identifiers provide a better uniqueness guarantee than sequence generators, which are only unique within a single database.

A UUID is written as a sequence of lower-case hexadecimal digits, in several groups separated by hyphens, specifically a group of 8 digits followed by three groups of 4 digits followed by a group of 12 digits, for a total of 32 digits representing the 128 bits. An example of a UUID in this standard form is:

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

GaussDB also accepts the following alternative forms for input: use of upper-case letters and digits, the standard format surrounded by braces, omitting some or all hyphens, and adding a hyphen after any group of four digits. An example is provided as follows:

A0EEBC99-9C0B-4EF8-BB6D-6BB9BD380A11
{a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11}
a0eebc999c0b4ef8bb6d6bb9bd380a11
a0ee-bc99-9c0b-4ef8-bb6d-6bb9-bd38-0a11

Output is always in the standard form.

-- Create a table.
gaussdb=# CREATE TABLE uuid_test(id int, test uuid) DISTRIBUTE BY HASH(test);

-- Insert data in the example format.
gaussdb=# INSERT INTO uuid_test VALUES(1, 'A0EEBC99-9C0B-4EF8-BB6D-6BB9BD380A11');
gaussdb=# INSERT INTO uuid_test VALUES(2, '{a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11}');
gaussdb=# INSERT INTO uuid_test VALUES(3, 'a0eebc999c0b4ef8bb6d6bb9bd380a11');
gaussdb=# INSERT INTO uuid_test VALUES(4, 'a0ee-bc99-9c0b-4ef8-bb6d-6bb9-bd38-0a11');

-- View data and output the data in the standard format.
gaussdb=# SELECT * FROM uuid_test;
 id |                 test                 
----+--------------------------------------
  1 | a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11
  2 | a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11
  3 | a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11
  4 | a0eebc99-9c0b-4ef8-bb6d-6bb9bd380a11
(4 rows)