On 01/01/2015 06:13 PM, Federico Razzoli wrote:
Morgan Tocker asked the community's opinions about SHOW ENGINE INNODB MUTEX: http://www.tocker.ca/2013/11/28/show-engine-innodb-mutex.html
Despite these opinions, as Valerii Kravchuk notes on Facebook, the command disappeared in the latest 5.7 release. He also notes that the command has never been deprecated (!).
Question is: will MariaDB preserve this command? Frankly, I don't know any other convenient way to obtain the same information... The main reason in favour of its removal in MySQL seems to be this point:
"The InnoDB mutex code was recently refactored as part of our server cleanup. After refactoring, the InnoDB code can now mix several mutex types internally including spin locks, system mutexes (POSIX) and InnoDB home brewed ones. The display output for |SHOW ENGINE INNODB MUTEX| doesn't really account for these differences in its status column. Grouping all mutex types together becomes less intuitive, and would require either some change to the output, or a coarse (inaccurate) mixing of the types:" The performance schema however is less intuitive to use, and, as was noted in the MySQL announcement of the removal, doesn't yet include spinning information. There's a post on Percona's blog that looks at getting similar information using the Performance Schema: http://www.percona.com/blog/2015/01/06/getting-mutex-information-from-mysqls... Much depends on what happens with XtraDB's implementation, but I wouldn't be in favour of just removing it without notice, as happened in MySQL 5.7. It should at least be deprecated. ian