The Ultimate Guide to High Availability with MariaDB

UUID_SHORT

Stai visualizzando una vecchia versione di questo article. Visualizza la versione più recente.

Sintassi

UUID_SHORT()

Spiegazione

Restituisce un universal identifier "breve", un intero senza segno di 64 bit (invece della stringa di 128 bit restituita dalla funzione UUID()).

Il valore di UUID_SHORT() è sicuramente unico, finché sussistono le seguenti condizioni:

  • 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++;

Examples:

MariaDB [(none)]> SELECT UUID_SHORT();
+-------------------+
| UUID_SHORT()      |
+-------------------+
| 21517162376069120 |
+-------------------+

See also

  • UUID() ; Return full (128 bit) Universal Unique Identifier

Commenti

Sto caricando i commenti......
Content reproduced on this site is the property of its respective owners, and this content is not reviewed in advance by MariaDB. The views, information and opinions expressed by this content do not necessarily represent those of MariaDB or any other party.