Multi-key transactions for consistency in Redis - Mini Project: Build & Apply

Multi-key Transactions for Consistency in Redis

📖 Scenario: You are managing a simple bank system where users have accounts with balances stored in Redis. You want to ensure that when transferring money from one user to another, the balances update correctly and consistently, even if multiple transfers happen at the same time.

🎯 Goal: Build a Redis transaction that safely transfers money between two user accounts by updating both balances atomically.

📋 What You'll Learn

Create two keys representing user balances with exact names and values

Set a transfer amount variable

Use Redis MULTI/EXEC commands to perform the transfer atomically

Ensure the transaction updates both user balances correctly

💡 Why This Matters

🌍 Real World

Banking and financial applications require consistent updates to multiple related data points, like account balances, to avoid errors and data corruption.

💼 Career

Understanding Redis transactions is essential for backend developers working with real-time data stores to maintain data integrity during concurrent operations.

1

DATA SETUP: Create user balance keys

Create two Redis keys called user:Alice:balance and user:Bob:balance with values 1000 and 500 respectively using the SET command.

Redis

# Your code here

Need a hint?

Use the SET command to assign the initial balances.

2

CONFIGURATION: Define the transfer amount

Create a Redis key called transfer:amount and set its value to 200 using the SET command.

Redis

SET user:Alice:balance 1000
SET user:Bob:balance 500
# Your code here

Need a hint?

Use SET transfer:amount 200 to define the amount to transfer.

3

CORE LOGIC: Start a transaction to transfer money

Start a Redis transaction with MULTI. Then use DECRBY user:Alice:balance 200 and INCRBY user:Bob:balance 200 to subtract and add the transfer amount. Do not execute the transaction yet.

Redis

SET user:Alice:balance 1000
SET user:Bob:balance 500
SET transfer:amount 200
# Your code here

Need a hint?

Use MULTI to start the transaction, then queue the decrement and increment commands.

4

COMPLETION: Execute the transaction

Complete the Redis transaction by adding the EXEC command to execute all queued commands atomically.

Redis

SET user:Alice:balance 1000
SET user:Bob:balance 500
SET transfer:amount 200
MULTI
DECRBY user:Alice:balance 200
INCRBY user:Bob:balance 200
# Your code here

Need a hint?

Use EXEC to run the transaction and apply all changes atomically.