Clearing Redis Cache: Step-by-Step Guide to Safely Remove Data Stored in Redis

Date: 28-02-2023

What is Redis?

Redis is an open-source, in-memory data structure store that can be used as a database, cache, and message broker.

It is known for its fast read and write speeds and can be used to improve application performance by caching frequently accessed data.

However, sometimes it may be necessary to clear the cache from Redis to ensure that the most up-to-date data is being used.

Before we begin, it is important to note that clearing the cache from Redis will remove all the keys in the currently selected database.

This means that all the data stored in Redis will be lost. It is crucial to make sure that you are selecting the correct database and that you have a backup of the data.

So stick to your seat and let’s begin with understanding the steps to be followed for clearing caches from Redis on the azure devops server below.

Steps to clear the cache from Redis

Here are the steps to clear the cache from Redis.

Step 1: Connect to the Redis Server

To clear the cache from Redis, you need to connect to the Redis server using a Redis client or command-line interface. 

If you are using a Redis client, you can connect to the Redis server by specifying the host, port, and password (if required). 

If you are using a command-line interface, you can connect to the Redis server by running the following command:

redis-cli -h host -p port -a password

Replace “host” with the IP address or hostname of the Redis server, “port” with the Redis port number, and “password” with the Redis password (if required).

Step 2: Select the Database

After connecting to the Redis server, you need to select the database you want to clear. 

Redis supports multiple databases, and each database is identified by a number from 0 to 15. You can select a database by running the following command:

SELECT database_number

Replace “database_number” with the number of the database you want to select. For example, to select database 0, you would run the following command:

SELECT 0

Step 3: Clear the Cache

Once you have selected the database, you can clear the cache by running the FLUSHDB command. 

This command will remove all the keys in the selected database. 

You can run the command by typing the following command:

FLUSHDB

After running this command, all the data stored in the selected database will be deleted.

Step 4: Confirm the Cache has Been Cleared

To confirm that the cache has been cleared, you can run the DBSIZE command, which will return the number of keys in the selected database. If the cache has been cleared successfully, the output of the DBSIZE command should be 0.

DBSIZE

Thereby, using these 4 steps you can successfully clear up all the Redis cache, and have your DevOps systems optimized for utmost performance.

Performance Impacts of Cache Clearing

One important consideration when clearing the Redis cache is the potential impact on application performance. Depending on the size of the cache and the number of keys being cleared, the process can be resource-intensive and may cause a temporary slowdown in application performance.

How To Minimise Performance Impact

To minimize the impact on performance, it is important to follow best practices when clearing the Redis cache. One such practice is to use the FLUSHDB command instead of the FLUSHALL command. 

The FLUSHDB command clears only the keys in the selected database, while the FLUSHALL command clears all the keys in all the databases. By using the FLUSHDB command, you can minimize the impact on performance by only clearing the keys that need to be updated.

Another best practice is to perform the cache-clearing operation during off-peak hours when application usage is lower. This can help to minimize the impact on performance and ensure that users are not impacted by slowdowns or other issues.

Additional Tips

Finally, it is important to have a backup strategy in place to ensure that data is not lost in the event of a cache-clearing error or other issues. Redis supports several backup strategies, including snapshotting and replication, which can be used to ensure data integrity and availability.

Conclusion

In conclusion, clearing the Redis cache is an important maintenance task that can help to ensure application performance and data integrity. By following best practices and using caution when clearing the cache, you can minimize the impact on performance and ensure that data is not lost.

Clearing the cache from Redis is a simple process that can be done by following the above steps. However, it is important to be cautious when clearing the cache as it will remove all the data stored in the selected database. Always make sure that you have a backup of the data if needed and that you are selecting the correct database before clearing the cache.