MongoDB introduced multi-document atomicity, consistency, isolation, and durability (ACID) transactions in version 4.0, which was released in July 2018. Transactions are an integral part of relational databases. Every relational database management system (RDBMS) from the very early days relied on transactions to achieve ACID. Getting these in a non-relational database is a breakthrough that can fundamentally change the way developers and database architects design software systems.

In the previous chapter, we learned how to query MongoDB using Ruby, Python, and PHP drivers and frameworks. In this chapter, we will learn about the following topics:

• Multi-document ACID transactions 
• Using transactions with Ruby and Python