UUID_SHORT
Syntax
UUID_SHORT()
Contents
Description
Returns a "short" universally unique 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 mariadbd restarts
- You do not invoke
UUID_SHORT()
on average more than 16 million times per second between mariadbd 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
- UUID() ; Return full (128 bit) Universally Unique Identifier
- AUTO_INCREMENT
- Sequences - an alternative to auto_increment available from MariaDB 10.3
- SYS_GUID - UUID without the
-
character for Oracle compatibility - UUID data type
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