How to detect database changes when redis is caching

Question: How does the Redis cache invalidation mechanism sense database changes? Answer: Redis provides the following mechanisms to invalidate the cache: Use the KEYS command to find the key containing the updated data identifier Use the EXPIRE command to set the expiration time of the key associated with the updated record Use pub/sub to subscribe to record update notifications and invalidate the cache key Use Lua script periodically checks for data changes and invalidates cache keys. Simplifies cache invalidation management using third-party libraries

Redis cache invalidation mechanism

When using Redis as a cache, it is crucial to sense database changes so that the cache can be invalidated in time when the database data is updated. Redis provides several mechanisms to achieve this:

1. Use the KEYS command

The KEYS command can return all keys that match the specified pattern, so it can be used for lookups A key containing a specific data source identifier (such as a database record ID). When the corresponding records in the database change, the KEYS command can be executed periodically to find the changed keys and invalidate them.

2. Use the EXPIRE command

The EXPIRE command can set the expiration time for the key. You can set a shorter expiration time for the Redis key associated with the record when the corresponding record in the database changes. In this way, when the database data is updated, the keys in the cache will automatically become invalid.

3. Use subscription pub/sub

#Redis's pub/sub mechanism allows applications to subscribe to a channel. When the corresponding record in the database changes, a message can be published to this channel. Clients subscribed to the channel (such as the Redis cache service) can receive the message and invalidate the associated cache key.

4. Using Lua scripts

Lua scripts provide the flexibility to perform complex operations on the Redis server. Lua scripts can be written to periodically check the database for changes to specific data and invalidate cache keys if needed.

5. Use third-party libraries

There are also many third-party libraries available to simplify Redis cache invalidation. These libraries typically provide higher-level APIs to manage cache invalidation, such as timestamp or database event-based invalidation mechanisms.

Choosing the Appropriate Mechanism

Choosing the appropriate invalidation mechanism depends on the specific needs of the application. For large update operations or real-time data, subscribing to pub/sub or using Lua scripts may be the best option. For less frequent update operations, the KEYS command or the EXPIRE command may be sufficient.

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