How to Get All Keys in Redis Using Command Line Interface? [2 Best Methods]

Written by

Ojash

Reviewed by

Akshat

Last updated: May 10, 2024

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If you’re trying to manage Redis keys using the command line, it can feel a bit tricky, especially with a large database or unexpected issues. In this guide, I’ll show you how to effectively use the KEYS and SCAN commands so you can easily get all keys in Redis or find specific ones. Whether you’re working in a small test environment or managing keys in a busy production setting, this guide will help streamline your process. I’ll walk through each command step-by-step, covering everything from initiating a connection to handling the output.

What are Keys in Redis?

Keys in Redis are unique identifiers that help you store, retrieve, and manage various types of data, such as strings, lists, sets, and hashes. Each key is paired with a value and is distinct within a Redis database. This unique setup allows for quick data operations and retrieval.

Redis keys can also have an expiry time, known as Time to Live (TTL). This feature lets you set a duration after which the key automatically deletes itself, making it useful for temporary data storage like session information or cache management. This ensures that the database uses memory efficiently by removing outdated or unnecessary data automatically.

How to Get All Keys in Redis?

That was the quick answer. Here is the detailed step-by-step guide for each method to get all keys in Redis CLI:

1. KEYS Command

The KEYS command in Redis is used to retrieve all the keys matching a specified pattern. This command is straightforward and useful for debugging or when you need a quick glance at what keys are in your database during the development phases. Follow these steps:

1. Open your Terminal on Ubuntu and connect to Redis by typing the command:

redis-cli

It will connect you to your Redis server via the command line interface.

2. To list all keys in your Redis database, execute the command:

KEYS *

This command will return a list of all keys. 

3. If you are looking for keys that match a specific pattern, replace * with your pattern, such as user* for all keys that start with user.

2. SCAN Command

The SCAN command is a cursor-based iterator that allows you to iterate over the key space incrementally. This command is designed to provide a non-blocking way to scan through keys, making it suitable for use even in production environments with large datasets. Here is the step-by-step guide:

1. Start by accessing your Redis CLI on your Ubuntu system.
2. Initiates the scan operation from the beginning of the database.

127.0.0.1:6379> SCAN 0

The SCAN command will return two elements: the new cursor position and an array of keys. 

3. If there are more keys that cannot be scanned in one go then continue issuing the SCAN command with the new cursor until it returns 0, indicating no more keys to scan.
4. Collect keys from each output array until all keys have been scanned.

5. Use the MATCH option to filter keys by a specific pattern during scanning, similar to KEYS but more efficiently:

SCAN 0 MATCH user*

Filters the scan results to only include keys that match the specified pattern.

Common Issues When Listing Keys in Redis

Working with Redis, especially when listing keys using the Command Line Interface on Ubuntu, you might run into a few common issues. Whether it’s a technical glitch, slow performance, or access issues, I will help you to fix them quickly and keep your Redis database running smoothly. Here’s how you can identify and resolve these problems:

• 🔄 High CPU Usage: The KEYS command might cause your CPU to spike if your database is large. This happens because KEYS scans every key in your database. To resolve this replace KEYS with SCAN, which processes keys in batches, reducing the load on your CPU and maintaining server responsiveness.
• 🚫 Command Blocked: Using KEYS can freeze your Redis because it locks the database while scanning. This blockage stops other commands from executing until it’s done. Opt for the SCAN command that allows the database to handle other operations simultaneously by breaking the task into smaller parts.
• 📊 Incomplete Key Listings: You might think SCAN is skipping keys if you don’t follow through the entire cursor cycle until it resets to 0. Always continue to run SCAN until the cursor output is 0, ensuring you have covered the entire database.
• 🔒 Permission Errors: If you can’t access certain keys, it might be due to restricted permissions set in Redis. Review and modify the Redis Access Control Lists (ACLs) to provide the necessary permissions for your user account to access or modify the keys.
• 🐌 Slow Response Times: When you use SCAN with a low count, especially in large databases, it can slow down responses. Increase the COUNT parameter in the SCAN command to fetch more keys per batch, speeding up the process while ensuring it doesn’t overload your system.
• 🧩 Pattern Mismatch: If you can’t find keys with the MATCH option, your pattern might not match the actual keys. Double-check your pattern for errors and ensure it accurately reflects the naming convention used in your Redis keys.
• 🔗 Connection Issues: Problems with connecting to Redis via CLI often arise if Redis isn’t running or if there’s a configuration error. Verify that the Redis server is active (sudo systemctl status redis) and check your connection parameters (host, port, password) to ensure they are correct.
• 📑 Output Overload: Getting too many keys at once can be overwhelming and hard to handle manually. Use shell scripting to handle large outputs. For example, you can pipe SCAN results into tools like grep for filtering or redirect output to a file for easier processing (SCAN 0 MATCH user:* > redis_keys.txt).

Conclusion

In this guide, I walked you through using the KEYS and SCAN commands to get all keys in Redis keys on Ubuntu. We also looked at some common issues you might face and how to solve them. These tools and tips are crucial for keeping your Redis database running smoothly.

To further enhance your skills with Redis on Ubuntu, consider exploring topics that build on your current knowledge. Learn how to use the grep OR condition to refine command-line searches. Explore listing all services in Ubuntu, which will aid in managing and troubleshooting Redis effectively. Also, mastering the systemctl command can provide deeper control over your system’s services, including Redis.

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