UUID_SHORT

Syntax

UUID_SHORT()

Description

Returns a "short" universal identifier as a 64-bit unsigned integer (rather than a string-form 128-bit identifier as returned by the UUID() function).

The value of UUID_SHORT() is guaranteed to be unique if the following conditions hold:

  • The server_id of the current host is unique among your set of master and slave servers
  • server_id is between 0 and 255
  • You don't set back your system time for your server between mysqld restarts
  • You do not invoke UUID_SHORT() on average more than 16 million times per second between mysqld restarts

The UUID_SHORT() return value is constructed this way:

  (server_id & 255) << 56
+ (server_startup_time_in_seconds << 24)
+ incremented_variable++;

Statements using the UUID_SHORT() function are not safe for statement-based replication.

Examples

SELECT UUID_SHORT();
+-------------------+
| UUID_SHORT()      |
+-------------------+
| 21517162376069120 |
+-------------------+
create table t1 (a bigint unsigned default(uuid_short()) primary key);
insert into t1 values(),();
select * from t1;
+-------------------+
| a                 |
+-------------------+
| 98113699159474176 |
| 98113699159474177 |
+-------------------+

See Also

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