After the first introduction to PostgreSQL 11, we want to focus our attention on the next important topic. Locking is a vital concept for any kind of database. It is not enough to understand just how it works to write proper or better applications, it is also essential from a performance point of view. Without handling locks properly, your applications might not only be slow, they might also be wrong and behave in very unexpected ways. In my opinion, locking is the key to performance and having a good overview will certainly help. Therefore, understanding locking and transactions is important for administrators and developers alike. In this chapter, you will learn about the following topics:

• Working with PostgreSQL transactions
• Understanding basic locking
• Making use of FOR SHARE and FOR UPDATE
• Understanding transaction isolation levels
• Considering serializable snapshot isolation (SSI) transactions
• Observing deadlocks and similar issues
• Optimizing storage and managing cleanups

At the end of the chapter, you will be able to understand and utilize PostgreSQL transactions in the most efficient way possible.