Delete Redis Keys by Prefix in Python (Detailed Guide w/ Code Examples)

Use Case(s)

Deleting keys by prefix in Redis is a common task when working with cache invalidation or data synchronization scenarios. It can be used to remove all keys that match a certain pattern, for example, delete all keys that start with 'user_profile' when user's profile information changes.

Code Examples

Let's assume we're using the redis-py client for Python.

import redis

r = redis.Redis(host='localhost', port=6379, db=0)

for key in r.scan_iter('user_profile*'):
    r.delete(key)

In this example, scan_iter is used to iteratively find keys that match the 'user_profile*' pattern. For each such key, we call delete method to remove it from Redis.

Best Practices

• Be mindful of using the delete operation in production applications, as it may affect performance, especially if the number of keys is large.
• It's recommended to use scan operations (like scan_iter) instead of the keys command for finding keys by pattern, as keys can block the server when called on large databases.

Common Mistakes

• A common mistake is to accidentally delete keys without ensuring the correct pattern. Always double-check your key patterns before deleting.
• Using the keys method instead of scan_iter could lead to performance issues. The keys method retrieves all keys and can be slow in large databases.

FAQs

Q: Can I undo a delete operation in Redis?

A: No, once a key is deleted, it cannot be recovered. Make sure to use the delete operation cautiously.

Q: What's the difference between keys and scan_iter commands?

A: The keys command retrieves all keys in the database at once and can block the server if the database is large. On the other hand, scan_iter uses a cursor to iteratively scan through the database, which is more efficient and recommended.