Querying Redis Eviction Policy in Python (Detailed Guide w/ Code Examples)

Use Case(s)

The eviction policy in Redis determines how Redis will handle data when the memory limit is reached. It's important to know your application's configured eviction policy, as it directly impacts how your application deals with potential memory issues.

Code Examples

To get the current eviction policy, we use the CONFIG GET command and pass 'maxmemory-policy' as the argument. Here's how you can do this using the redis-py library in Python:

import redis

r = redis.Redis(host='localhost', port=6379, db=0)
eviction_policy = r.config_get()['maxmemory-policy']
print(eviction_policy)

This script connects to the Redis server running on localhost at port 6379, then retrieves and prints the current eviction policy.

Best Practices

While setting the eviction policy, think about what kind of data you are storing and how critical it is for your application. Different eviction policies can have significant implications for your application's performance and behavior.

Common Mistakes

A common mistake is not considering the eviction policy when experiencing out-of-memory errors or unexpected data loss. Knowing and understanding your Redis instance's eviction policy can help troubleshoot these types of problems.

FAQs

Q: What are the different types of eviction policies in Redis?

A: They include noeviction, allkeys-lru, volatile-lru, allkeys-random, volatile-random, volatile-ttl.

Q: How do I set the eviction policy in Redis?

A: You can set it using the CONFIG SET command. For example: r.config_set('maxmemory-policy', 'allkeys-lru').