Re: Deadlock found when trying to get lock; Try restarting transaction, message from server: "Lock wait timeout exceeded; try restarting transaction" : for SELECT statement

[Ted Wennmark]

With NDB you need to tune some parameters like TransactionDeadlockDetectionTimeout to protect your cluster from long running transactions/queries like above, once you tuned it for worst case transaction/query you do not have to change them again.

Select statements do work concurrently, this is not a deadlock, it's a transaction timeout, NDB have no native method of detecting deadlocks so a transaction timeout can not be distinguished from a true deadlock, they both use value of TransactionDeadlockDetectionTimeout to abort the transaction. With NDB you normally want to have many concurrent short running transactions.