# SYS\_GUID and UUID

Generates and returns a new globally unique identifier (GUID) each time it is called.

## Syntax

```sql
SYS_GUID()

UUID()
```

## Return Type

`SYS_GUID`: `BINARY(16)`

`UUID`: `VARCHAR(36)`

## Remarks

* Returns a v4 UUID
* The value returned will be globally unique 
* A new value will be produced for each row processed
* A new value will be produced for each occurrence of the function in the query syntax
* `UUID` works exactly like `SYS_GUID` except for the return type
* `SYG_GUID`/`UUID` cannot be used as a default column value for a sharded table
* `SYS_GUID`/`UUID` cannot be used in a computed column expression in a table definition

> **📝 Note**: Use `INT` or `BIGINT` fields for joining tables if performance is the most important consideration. Joining on `BINARY(16)` columns works, but is noticeably slower. Rather than `UUID` or `SYS_GUID`, use `AUTO_INCREMENT`, or implement application code to provide integer key values on which to join tables, for the best performance.

## Examples

## SYS\_GUID Example

Create a simple table and insert a row. In order to display the `GUID`, convert it to `HEX`:

```sql
CREATE TABLE id_t(a INT, b BINARY(16));
INSERT id_t VALUES(1, SYS_GUID());

```

```sql
SELECT a, HEX(b) FROM id_t;

```

```output

+------+----------------------------------+
| a    | HEX(b)                           |
+------+----------------------------------+
|    1 | 7CD5B7769DF95CEFE034080020825436 |
+------+----------------------------------+
```

## UUID Example

```sql
CREATE TABLE id_t2(a INT, b VARCHAR(36));
INSERT INTO id_t2 VALUES(1, UUID());

```

```sql
SELECT * FROM id_t2;

```

```output

+------+--------------------------------------+
| a    | b                                    |
+------+--------------------------------------+
|    1 | 15c67225-38f9-483b-8394-02a9e35a9156 |
+------+--------------------------------------+
```

***

Modified at: November 12, 2024

Source: [/db/v9.1/reference/sql-reference/identifier-generation-functions/sys-guid-and-uuid/](https://docs.singlestore.com/db/v9.1/reference/sql-reference/identifier-generation-functions/sys-guid-and-uuid/)

(An index of the documentation is available at /llms.txt)