How do you ensure data relevance and prevent the use of outdated values in Redis?

To ensure data freshness in Redis and prevent the use of outdated values, the following approaches are used:

1. Setting Time To Live (TTL) — when a key is written in Redis, a TTL is assigned, after which the key is automatically deleted. This prevents the use of stale data.

2. Using cache invalidation mechanisms — when data in the primary database or source changes, the corresponding keys in Redis are deleted or updated.

3. Key versioning — adding a version or timestamp to keys so that when data is updated, it is possible to distinguish fresh values from outdated ones.

4. Using Pub/Sub or notifications — to synchronize changes between services and update the cache.

Example of setting TTL in Java using Jedis:

Jedis jedis = new Jedis("localhost");
// Set a key with a TTL of 60 seconds
jedis.setex("user:123", 60, "userData");

Thus, data will automatically be deleted after 60 seconds, helping to avoid the use of outdated values.