In this chapter, you were introduced to locking and transactions. As pointed out, locking is a central issue affecting both scalability as well as correctness of your data. It is important to keep an eye on locking. Especially, transaction isolation is an important issue, but is often forgotten by many developers, which in turn can lead to buggy applications. In addition to that, harsh locking can lead to scalability issues as well as to timeouts.

In addition to what you have seen, locks can be reverse engineered to find out who is waiting for whom.