The InnoDB deadlock monitor is a little different than the rest of the monitors and require a little additional explanation. Whereas all other monitors are based on the return of
SHOW GLOBAL STATUS,
SHOW GLOBAL VARIABLES and
SHOW SLAVE STATUS, the 'InnoDB deadlock' monitor is based on output from
SHOW ENGINE INNODB STATUS. This statement differs from the first-mentioned in the sense that it does not return as single discrete value (like a single number), but a rather long string instead with lots of information. From this long string we extract what is related to deadlocks.
With this monitor, it does not make sense to distinguish between 'Current' and 'Delta' timeframes. These timeframes display the same in SQL DM for MySQL:
- New Deadlock Detected indicates if a new deadlock was reported by INNODB STATUS between the last two data retrievals.
- Latest Deadlock Detected shows information about the last deadlock detected (if any). To view all deadlock situation that SQL DM for MySQL has information about, use the 'History' timeframe.
There is a limitation with deadlock information returned by
SHOW ENGINE INNODB STATUS that will also affect SQL DM for MySQL: It returns only information about the last deadlock. So if more than one deadlock has occurred between two data retrievals, SQL DM for MySQL only has information about the latest.