+1 =) mysql manual sometimes don't help, that's why i really prefer mariadb kb
i think that many years ago mysql implement this nontransactional like locks to innodb just to allow guys porting from myisam to innodb using old apps without rewriting the lock/unlock to begin/commit if you are using innodb as transactional you will never use lock/unlock, in my opnion maybe you probably only use locks at filesystem or use get_lock() mysql function or any other IPC function, but be carefull about scalability i don't know what's the 'best' lock server today, all shared locks that i use today i use over a filesystem and network (nfs/smb/others network file system), if get_lock work with galera maybe i could get a try 2014-09-23 6:51 GMT-03:00 Elena Stepanova <ele...@montyprogram.com>: > Hi Federico, > > On 23.09.2014 12:50, Federico Razzoli wrote: > >> Let's make the snippet simpler. Only one table, non-transactional, please >> look at the difference from what docs say and the real behaviour. If one >> could explain what UNLOCK TABLES exactly does, it would be great. >> >> MariaDB [test]> SELECT @@in_transaction, @@autocommit; >> +------------------+--------------+ >> | @@in_transaction | @@autocommit | >> +------------------+--------------+ >> | 0 | 1 | >> +------------------+--------------+ >> 1 row in set (0.00 sec) >> >> MariaDB [test]> CREATE OR REPLACE TABLE t (c INT) ENGINE = MEMORY; >> Query OK, 0 rows affected (0.12 sec) >> >> MariaDB [test]> LOCK TABLE t WRITE; >> Query OK, 0 rows affected (0.00 sec) >> >> MariaDB [test]> START TRANSACTION; >> Query OK, 0 rows affected (0.00 sec) >> > > "Beginning a transaction causes table locks acquired with LOCK TABLES to > be released, as though you had executed UNLOCK TABLES." > > http://dev.mysql.com/doc/refman/5.5/en/commit.html > > >> MariaDB [test]> INSERT INTO t VALUES (1); >> Query OK, 1 row affected (0.01 sec) >> >> MariaDB [test]> UNLOCK TABLES; >> Query OK, 0 rows affected (0.00 sec) >> > > So, this UNLOCK is not actually doing anything. > > Regards, > Elena > > > >> MariaDB [test]> SELECT @@in_transaction; >> +------------------+ >> | @@in_transaction | >> +------------------+ >> | 1 | >> +------------------+ >> 1 row in set (0.00 sec) >> >> >> Regards >> Federico >> >> >> _______________________________________________ >> Mailing list: https://launchpad.net/~maria-discuss >> Post to : maria-discuss@lists.launchpad.net >> Unsubscribe : https://launchpad.net/~maria-discuss >> More help : https://help.launchpad.net/ListHelp >> >> > _______________________________________________ > Mailing list: https://launchpad.net/~maria-discuss > Post to : maria-discuss@lists.launchpad.net > Unsubscribe : https://launchpad.net/~maria-discuss > More help : https://help.launchpad.net/ListHelp > -- Roberto Spadim SPAEmpresarial Eng. Automação e Controle
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