Introduction to Transactions and the Multi Module

Grouping operations

Throughout this course, we’ve been working with one database operation at a time. However, there are times when we have multiple operations that need to be treated as a group—they all need to succeed or fail together.

Example

A classic example is transferring money between two bank accounts. If we want to transfer $10 from Bob’s account and put it in Alice’s account (it’s always Bob and Alice for some reason), we have to perform two updates.

• Reducing Bob’s balance by 10.
• Increasing Alice’s balance by 10.

What would happen if the update to Bob’s balance succeeds but Alice’s balance fails? The accounts would be out of sync, and the $10 would effectively be missing.