What else can redis do besides caching?

Redis should be said to be one of the most popular NoSQL databases at present. Redis is usually used as a caching component to cache data. However, in addition to caching data, Redis can actually do many things. Here are a few examples for your reference.

1. Latest list (recommended learning: Redis video tutorial)

For example, for the latest news list on the news list page, if the total number is very large, try not to use select a from A limit 10. Try the LPUSH command of redis to build the List, and just insert them one by one in order. But what if the memory is cleared? It’s also simple. If you can’t query the storage key, just use mysql to query and initialize a List into redis.

2. Ranking application

The redis data type mainly used to implement this function is the redis ordered set zset. zset is an extension of the set type. It has one more sequence attribute than the original type. This attribute will automatically adjust the sequence value every time data is inserted to ensure that the value values ​​are continuously arranged in a certain order.

We assume it is a game experience value ranking list. The main implementation idea is:

When a new player participates in the game, add a new record to the zset in redis (Record content depends on specific requirements) score is 0

When the player's experience value changes, modify the player's score value

Use the ZREVRANGE method of redis to obtain the ranking

3. Counter application

Redis commands are all atomic. You can easily use INCR and DECR commands to perform atomic operations to build a counting system. Due to the single thread, concurrency issues can be avoided, error-free guaranteed, and 100% millisecond-level performance.

For example, in a web application, if you want to know the number of user clicks every day for a year, then you only need to use the user ID and related date information as keys, and execute it every time the user clicks on the page. One auto-increment operation is enough.

4. Data deduplication

Redis set can automatically deduplicate data. When you need to store a list of data and do not want duplicate data to appear, set is A good choice, and set provides an important interface for determining whether a member is in a set collection.

Implementation plan:

The internal implementation of set is a HashMap whose value is always null. In fact, it is quickly sorted by calculating hash. This is also what set can provide to determine whether a member is Reason within the set.

5. Real-time anti-spam system

Anti-spam systems are usually based on keywords. Redis is used to store related words, which can take advantage of the high performance of Redis. The monitoring system provides stable and accurate real-time monitoring functions. Typical cases include email systems, comment systems, etc.

6. Real-time messaging system that can publish and subscribe

The Pub/Sub system in Redis can build a real-time messaging system. For example, many are built using Pub/Sub Live chat application.

Design idea:

The server sends a message (including title, content), the title is stored in redis according to certain rules, and at the same time the title (with the minimum amount of information) is pushed to the client, and the customer clicks When reading the title, get the corresponding content to read.

If not read, you can prompt how many unread items, redis can quickly count

Clear the cache according to a certain period of time

Technical implementation:

Requires redis database, client websocket, server side websocket

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