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How to see the last deadlock in InnoDB?
To see the last deadlock in an InnoDB user transaction, use the SHOW ENGINE INNODB STATUS command. If frequent deadlocks highlight a problem with transaction structure or application error handling, run with the innodb_print_all_deadlocks setting enabled to print information about all deadlocks to the mysqld error log.
What does the status show on the InnoDB monitor?
Status: Shows the timestamp, monitor name and the number of seconds, or the elapsed time between the current time and the time the InnoDB Monitor output was last displayed. The per-second averages are based upon this time.
How to avoid and recover from deadlocks in MySQL?
For more information about avoiding and recovering from deadlock conditions, see Section 14.7.5.3, “How to Minimize and Handle Deadlocks” . When deadlock detection is enabled (the default) and a deadlock does occur, InnoDB detects the condition and rolls back one of the transactions (the victim).
What is the Log Sequence Number of InnoDB?
LOG: InnoDB log information, including current log sequence number, how far the log has been flushed to disk, the position at which InnoDB last took a checkpoint, pending writes and write performance statistics.
What to do in case of a deadlock in MySQL?
If deadlock detection is disabled using the innodb_deadlock_detect configuration option, InnoDB relies on the innodb_lock_wait_timeout setting to roll back transactions in case of a deadlock. Thus, even if your application logic is correct, you must still handle the case where a transaction must be retried.
Why are transactions unable to proceed in a deadlock?
A deadlock is a situation where different transactions are unable to proceed because each holds a lock that the other needs. Because both transactions are waiting for a resource to become available, neither ever release the locks it holds.
How are deadlocks affected by the isolation level?
WHERE statements. The possibility of deadlocks is not affected by the isolation level, because the isolation level changes the behavior of read operations, while deadlocks occur because of write operations. For more information about avoiding and recovering from deadlock conditions, see Section 14.7.5.3, “How to Minimize and Handle Deadlocks” .