Welcome back! In the previous lesson, we explored Redis Pipelines, which optimize command execution by batching multiple commands. Today, we’ll focus on Redis Transactions, a powerful feature that queues a group of commands for execution in a single, sequential operation.

By the end of this lesson, you will understand how to implement transactions in Redis using a conceptual approach.

Redis Transactions allow you to queue multiple commands and then execute them sequentially once you commit (using EXEC). This is often described as an atomic operation, but it’s important to note:

• Atomic Execution: Commands within a transaction are sent to Redis as a block.
• (Partial) All or Nothing: If a command fails at queue time (e.g., invalid command), the entire transaction is discarded. However, if a command fails at runtime (e.g., a type error), Redis will still execute the other commands. For example, if you queue syncCommands.set("key1", "value1") and syncCommands.incr("key1") in a transaction, and incr() fails at runtime due to key1 being non-numeric, the set() command will still execute. This demonstrates that atomicity in Redis transactions applies only to queuing, not to execution.
• Isolation: Transactions prevent other clients from executing commands on the keys being modified until the transaction completes.