Can a select operation result in a deadlock?

Can a select operation result in a deadlock?

So clearly a Select operation can cause a deadlock if join operations involving more than one table is a part of it. Usually Insert and Delete operations involve single relations.

What happens when transaction is deadlocked on lock resources?

Transaction (Process ID) was deadlocked on lock resources with another process and has been chosen as the deadlock victim. Rerun the transaction. and the killed session is rolled back. As a rule, the victim is the session that requires the least amount of overhead to rollback.

How does InnoDB deal with deadlocks in transactions?

In a transaction system, deadlocks are a fact of life and not completely avoidable. InnoDB automatically detects transaction deadlocks, rollbacks a transaction immediately and returns an error.

Where is the deadlock on MySQL insert statments?

IODKU must check all both unique keys — the PK and the one on rec_id. I think (without proof) that the deadlock is on rec_id. The only way for an AUTO_INCREMENT to get in trouble without UNIQUE is if you deliberately insert two rows with the same rec_id. If you never do such, INDEX is sufficient.

How does a deadlock on a resource list work?

If this was a classic lookup deadlock, the resource list will include both the Clustered Index and Non-Clustered Index. Typically the SELECT will hold a SHARED lock on the NC index and wait for a SHARED lock on the CI, meanwhile the INSERT will acquire an EXCLUSIVE lock on the CI and wait for an EXCLUSIVE lock on the NC.

What are the ingredients of a deadlock pattern?

The essential ingredients for this deadlock pattern are: The SELECT accesses the nonclustered index first, then the clustered index. The INSERT access the clustered index first, then the nonclustered index. Accessing the same resources in a different order acquiring incompatible locks is a great way to ‘achieve’ a deadlock of course.

Why are there two threads in the deadlock graph?

That leaves us to assume that this is a deadlock due to the Parallel Plan. The deadlock graph is not rendered properly, but if you look at the Deadlock XML, you can see that two threads from the SELECT statement (SPID 690) are involved in the deadlock .

Why are COL1 and COL2 together causing a deadlock?

Col1 and Col2 together form a composite primary key. I earlier thought it could be due to an index-record lock but the trace clearly shows that the statements that are blocking each other do not have any duplicate records. So why is it causing deadlock? These kind of deadlocks are known as Gap Locks.

Why did I get a deadlock in past?

Deadlock happened alot in my application at past due to mysql’s mechanisms. I solved it with two ways.

Which is a composite primary key in a multithreaded application?

I have a multithreaded application that tries to INSERT a record in a table in multiple batches. Each thread processing one batch. At times I get Deadlock error, following is the trace. Col1 and Col2 together form a composite primary key.