Re: Lock wait timeout exceeded - MySQL 5.6.15-ndb-7.3.4

[Peter Brawley]

> live telecom application, that would require an instant return instead of any "waits".

?! In a multi-user db app waits can't be prevented completely. You can only minimise them.

> Would it be possible under MySQL to prioritize the DELETE over UPDATE or vice versa. As that would take care of the deadlocks.

Do that in app code, eg set a semaphore that your transaction management module can read.

> decrease the deadlock frequency?

Have you studied http://dev.mysql.com/doc/refman/5.6/en/mysql-cluster-limitations-transactions.html?

After that, the biggest thing is to minimise transaction duration eg ...

- make transactions as atomic as possible

- don't start the transaction until the user has hit Save|Delete

- don't go overboard on indexes that slow down updates

I'm moving this to the NDBcluster forum, where there may be more help on the subject.