I’m often wondering what version of the InnoDB Plugin is included with which version of MySQL (or MariaDB). The MySQL changelogs used to denote which version of the InnoDB plugin was included with that particular release of MySQL, but sadly this is no longer the case.

Therefore I’ve compiled a comprehensive list which contains all of this info, and then some (and note all InnoDB Plugin changelog links are provided at the bottom).

Hope you find it helpful

MySQL 5.6:

When InnoDB appears hung, I know the natural reaction is to check SHOW ENGINE INNODB STATUS.

In fact, it’s the first thing I check when InnoDB tables are involved.

However, I just want to iterate how valuable SHOW FULL PROCESSLIST and/or mysqladmin debug outputs can be even when it seems mysqld is hung on on InnoDB table.

Two recent cases I’ve encountered illustrate why.

Case #1:

MySQL appeared hung on the following simple, single-row INSERT:

---TRANSACTION 0 2035648699, ACTIVE 76629 sec, process no 9047,
OS thread id 3069426592, thread declared inside InnoDB 500
mysql tables in use 1, locked 1
...
INSERT INTO test (id, parent, text) VALUES (180370, 70122, 'test table')

At least that’s what it seemed per the INNODB STATUS, but unfortunately, there wasn’t any further information to go on.

The next time it occurred, SHOW FULL PROCESSLIST was captured at the time.

…

One common cause for deadlocks when using InnoDB tables is from the existence of foreign key constraints and the shared locks (S-lock) they acquire on referenced rows.

The reason I want to discuss them though is because they are often a bit tricky to diagnose, especially if you are only looking at the SHOW ENGINE INNODB STATUS output (which might be a bit counter-intuitive since one would expect it to contain this info).

Let me show a deadlock error to illustrate (below is from SHOW ENGINE INNODB STATUS\g):

------------------------
LATEST DETECTED DEADLOCK
------------------------
111109 20:10:03
*** (1) TRANSACTION:
TRANSACTION 65839, ACTIVE 19 sec, OS thread id 4264 starting index read
mysql tables in use 1, locked 1
LOCK WAIT 6 lock struct(s), heap size 1024, 3 row lock(s), undo log entries 1
MySQL thread id 3, query id 74 localhost 127.0.0.1 root Updating
UPDATE parent SET age=age+1 WHERE id=1
*** (1) WAITING FOR THIS LOCK TO BE …

This presentation was be done by Sheeri Cabral of The Pythian Group and went into how to use SHOW ENGINE INNODB STATUS to get more information about your Innodb tables, foreign keys and transactions. This is a great presentation to learn how InnoDB works.

It also went through how to use SHOW ENGINE INNODB STATUS to tune several InnoDB variables:

innodb_adaptive_hash_index
innodb_commit_concurrency
innodb_concurrency_tickets
innodb_file_io_threads
innodb_log_buffer_size
innodb_max_purge_lag
innodb_sync_spin_loops
innodb_thread_concurrency
innodb_thread_sleep_delay

The slides can be downloaded from:

http://technocation.org/files/doc/ShowEngineInnoDBStatus.pdf

(Note that the slides open up to the middle section, which …

On Monday, October 12, 2009* from 7-9 pm at MIT, I will be giving a presentation explaining SHOW ENGINE INNODB STATUS for the Boston MySQL User Group. There is information about foreign keys, transactions, deadlocks and mutexes just waiting to be discovered, and I will show how to decipher the information.

For all those in the Boston area, I hope to see you there! For those who cannot be there, we will video this presentation and make it available online, and post here when the video/slides are up.

*Yes, I realize that this is a bank holiday in the US.

If you use innodb_file_per_table = 1 and innodb_open_files = X (whatever amount is suitable for your server) there’s no way internal to MySQL for finding out how many IBD files InnoDB actually has open. Neither SHOW GLOBAL STATUS LIKE ‘innodb%’ nor SHOW ENGINE INNODB STATUS provide this information.

Many sites do have a growing number of tables, so you’ll want to know when it’s time to up the number (and potentially also open-files-limit). Solution: sudo lsof | grep -c “\.ibd$”