OBJECT ENCODING for internal encoding in Redis - Mini Project: Build & Apply

Understanding Redis OBJECT ENCODING for Internal Encoding

📖 Scenario: You are managing a Redis database for a small online store. You want to understand how Redis stores different types of data internally to optimize memory usage and performance.

🎯 Goal: Learn how to check the internal encoding of Redis keys using the OBJECT ENCODING command and interpret the results.

📋 What You'll Learn

Create Redis keys with different data types

Use the OBJECT ENCODING command to check internal encoding

Understand the meaning of common encoding types like int, raw, and ziplist

Practice retrieving encoding information for multiple keys

💡 Why This Matters

🌍 Real World

Understanding Redis internal encoding helps optimize memory and performance in real applications like caching, session storage, and real-time analytics.

💼 Career

Redis is widely used in backend development and DevOps roles; knowing how to inspect and optimize data storage is a valuable skill.

1

Create Redis keys with different data types

Create three Redis keys with these exact names and values: user:1 with string value "Alice", visits with integer value 100, and cart:1 as a list with values "apple" and "banana".

Redis

# Your Redis commands here

Need a hint?

Use SET for strings and integers, and RPUSH to create a list.

2

Add a helper variable for keys to check

Create a Redis list key called keys_to_check and add the three keys user:1, visits, and cart:1 as its elements.

Redis

SET user:1 "Alice"
SET visits 100
RPUSH cart:1 "apple" "banana"
# Add the keys to the list keys_to_check

Need a hint?

Use RPUSH to add multiple elements to the list keys_to_check.

3

Check internal encoding of each key

Use the OBJECT ENCODING command to find the internal encoding of each key: user:1, visits, and cart:1. Write one command per key.

Redis

SET user:1 "Alice"
SET visits 100
RPUSH cart:1 "apple" "banana"
RPUSH keys_to_check "user:1" "visits" "cart:1"
# Use OBJECT ENCODING for each key

Need a hint?

Use OBJECT ENCODING keyname to check each key's encoding.

4

Complete by retrieving encoding info for all keys in the list

Write a Redis Lua script that loops over the list keys_to_check and returns a table with each key and its internal encoding using redis.call('OBJECT', 'ENCODING', key).

Redis

SET user:1 "Alice"
SET visits 100
RPUSH cart:1 "apple" "banana"
RPUSH keys_to_check "user:1" "visits" "cart:1"
OBJECT ENCODING user:1
OBJECT ENCODING visits
OBJECT ENCODING cart:1
-- Write Lua script here

Need a hint?

Use LRANGE to get keys, loop with ipairs, call OBJECT ENCODING inside the loop, and collect results in a table.