The UUID (Universally Unique Identifier) data type stores a 128-bit value that is unique across both space and time.
To auto-generate unique row identifiers, use UUID with the gen_random_uuid() function as the default value. See the example below for more details.
Syntax
You can express UUID values using the following formats:
| Format | Description |
|---|---|
| Standard RFC4122 format | Hyphen-separated groups of 8, 4, 4, 4, and 12 hexadecimal digits. Example: acde070d-8c4c-4f0d-9d8a-162843c10333 |
BYTES |
UUID value specified as a BYTES value.Example: b'kafef00ddeadbeed' |
| Uniform Resource Name | A Uniform Resource Name (URN) specified as "urn:uuid:" followed by the RFC4122 format. Example: urn:uuid:63616665-6630-3064-6465-616462656564 |
| Alternate PostgreSQL-supported formats | All alternate UUID formats supported by PostgreSQL, including the RFC4122 format surrounded by braces, any supported format with upper-case digits, any supported format with some or all hyphens omitted, and any supported format with hyphens after any group of four digits.Examples: {acde070d-8c4c-4f0d-9d8a-162843c10333}, ACDE070D-8C4C-4f0D-9d8A-162843c10333, acde070d8c4c4f0d9d8a162843c10333, acde-070d-8c4c-4f0d-9d8a-1628-43c1-0333 |
CockroachDB displays all UUID values in the standard RFC4122 format.
Size
A UUID value is 128 bits in width, but the total storage size is likely to be larger due to CockroachDB metadata.
Examples
Create a table with manually-entered UUID values
Create a table with UUID in standard RFC4122-specified format
> CREATE TABLE v (token uuid);
> INSERT INTO v VALUES ('63616665-6630-3064-6465-616462656562');
> SELECT * FROM v;
token
----------------------------------------
63616665-6630-3064-6465-616462656562
(1 row)
Create a table with UUID in BYTE format
> INSERT INTO v VALUES (b'kafef00ddeadbeed');
> SELECT * FROM v;
token
----------------------------------------
63616665-6630-3064-6465-616462656562
6b616665-6630-3064-6465-616462656564
(2 rows)
Create a table with UUID used as URN
> INSERT INTO v VALUES ('urn:uuid:63616665-6630-3064-6465-616462656564');
> SELECT * FROM v;
token
----------------------------------------
63616665-6630-3064-6465-616462656562
6b616665-6630-3064-6465-616462656564
63616665-6630-3064-6465-616462656564
(3 rows)
Express UUIDs in alternate formats
> INSERT INTO v VALUES ('{acde070d-8c4c-4f0d-9d8a-162843c10333}'), ('ACDE070D-8C4C-4f0D-9d8A-162843c10333'), ('acde070d8c4c4f0d9d8a162843c10333'), ('acde-070d-8c4c-4f0d-9d8a-1628-43c1-0333');
> SELECT * FROM v;
token
----------------------------------------
63616665-6630-3064-6465-616462656562
6b616665-6630-3064-6465-616462656564
63616665-6630-3064-6465-616462656564
acde070d-8c4c-4f0d-9d8a-162843c10333
acde070d-8c4c-4f0d-9d8a-162843c10333
acde070d-8c4c-4f0d-9d8a-162843c10333
acde070d-8c4c-4f0d-9d8a-162843c10333
(7 rows)
Create a table with auto-generated unique row IDs
To auto-generate unique row identifiers, use the UUID column with the gen_random_uuid() function as the default value:
> CREATE TABLE users (
id UUID NOT NULL DEFAULT gen_random_uuid(),
city STRING NOT NULL,
name STRING NULL,
address STRING NULL,
credit_card STRING NULL,
CONSTRAINT "primary" PRIMARY KEY (city ASC, id ASC),
FAMILY "primary" (id, city, name, address, credit_card)
);
> INSERT INTO users (name, city) VALUES ('Petee', 'new york'), ('Eric', 'seattle'), ('Dan', 'seattle');
> SELECT * FROM users;
id | city | name | address | credit_card
+--------------------------------------+----------+-------+---------+-------------+
cf8ee4e2-cd74-449a-b6e6-a0fb2017baa4 | new york | Petee | NULL | NULL
2382564e-702f-42d9-a139-b6df535ae00a | seattle | Eric | NULL | NULL
7d27e40b-263a-4891-b29b-d59135e55650 | seattle | Dan | NULL | NULL
(3 rows)
Alternatively, you can use the BYTES column with the uuid_v4() function as the default value instead:
> CREATE TABLE users2 (
id BYTES DEFAULT uuid_v4(),
city STRING NOT NULL,
name STRING NULL,
address STRING NULL,
credit_card STRING NULL,
CONSTRAINT "primary" PRIMARY KEY (city ASC, id ASC),
FAMILY "primary" (id, city, name, address, credit_card)
);
> INSERT INTO users2 (name, city) VALUES ('Anna', 'new york'), ('Jonah', 'seattle'), ('Terry', 'chicago');
> SELECT * FROM users;
id | city | name | address | credit_card
+------------------------------------------------+----------+-------+---------+-------------+
4\244\277\323/\261M\007\213\275*\0060\346\025z | chicago | Terry | NULL | NULL
\273*t=u.F\010\274f/}\313\332\373a | new york | Anna | NULL | NULL
\004\\\364nP\024L)\252\364\222r$\274O0 | seattle | Jonah | NULL | NULL
(3 rows)
In either case, generated IDs will be 128-bit, large enough for there to be virtually no chance of generating non-unique values. Also, once the table grows beyond a single key-value range (more than 512 MiB by default), new IDs will be scattered across all of the table's ranges and, therefore, likely across different nodes. This means that multiple nodes will share in the load.
This approach has the disadvantage of creating a primary key that may not be useful in a query directly, which can require a join with another table or a secondary index.
If it is important for generated IDs to be stored in the same key-value range, you can use an integer type with the unique_rowid() function as the default value, either explicitly or via the SERIAL pseudo-type:
> CREATE TABLE users3 (
id INT DEFAULT unique_rowid(),
city STRING NOT NULL,
name STRING NULL,
address STRING NULL,
credit_card STRING NULL,
CONSTRAINT "primary" PRIMARY KEY (city ASC, id ASC),
FAMILY "primary" (id, city, name, address, credit_card)
);
> INSERT INTO users3 (name, city) VALUES ('Blake', 'chicago'), ('Hannah', 'seattle'), ('Bobby', 'seattle');
> SELECT * FROM users3;
id | city | name | address | credit_card
+--------------------+---------+--------+---------+-------------+
469048192112197633 | chicago | Blake | NULL | NULL
469048192112263169 | seattle | Hannah | NULL | NULL
469048192112295937 | seattle | Bobby | NULL | NULL
(3 rows)
Upon insert or upsert, the unique_rowid() function generates a default value from the timestamp and ID of the node executing the insert. Such time-ordered values are likely to be globally unique except in cases where a very large number of IDs (100,000+) are generated per node per second. Also, there can be gaps and the order is not completely guaranteed.
For further background on UUIDs, see What is a UUID, and Why Should You Care?.
Supported casting and conversion
UUID values can be cast to the following data type:
| Type | Details |
|---|---|
BYTES |
Requires supported BYTES string format, e.g., b'\141\061\142\062\143\063'. |
See also
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