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What are the 11 Web application scenarios of Redis? many novices are not very clear about this. In order to help you solve this problem, the following editor will explain it in detail. People with this need can come and learn. I hope you can get something.

Some Redis primitive commands such as LPUSH, LTRIM, and LREM can be used to help developers accomplish the tasks they need, which are very difficult or slow in traditional database storage. So how do you accomplish these tasks in your framework?

The following list of 11 Web application scenarios, in these scenarios can make full use of the characteristics of Redis, greatly improve efficiency.

1. Display the latest list of projects on the home page

Redis uses a resident memory cache, which is very fast. LPUSH is used to insert a content ID, which is stored as a keyword in the list header. LTRIM is used to limit the number of items in the list to a maximum of 5000. If the amount of data retrieved by the user exceeds the cache capacity, the request needs to be sent to the database.

two。 Delete and filter

If an article is deleted, it can be completely erased from the cache using LREM.

3. Ranking and related questions

The ranking (leader board) is sorted by score. The ZADD command can achieve this function directly, while the ZREVRANGE command can be used to get the top 100 users according to their scores, and ZRANK can be used to obtain user rankings, which is very direct and easy to operate.

4. Sort by user vote and time

It's like the Reddit rankings, where scores change over time. The LPUSH and LTRIM commands are used together to add articles to a list. A background task is used to get the list and recalculate the order of the list, and the ZADD command is used to populate the generated list in the new order. Lists can be retrieved very quickly, even on heavily loaded sites.

5. Overdue project processing

Use unix time as the keyword to keep the list sorted by time. Search current_time and time_to_live to complete the arduous task of finding overdue items. Another background task uses ZRANGE...WITHSCORES to query and delete expired entries.

6. Count

There are a wide range of uses for data statistics, such as knowing when to block an IP address. The INCRBY command makes it easy to keep counting by atomic increments; GETSET is used to reset counters; and expiration attributes are used to confirm when a keyword should be deleted.

7. Specific projects within a specific period of time

This is a problem for specific visitors and can be solved by using the SADD command for each page browse. SADD does not add existing members to a collection.

8. Real-time analysis of what is happening, for data statistics and prevention of spam, etc.

Using Redis primitive commands, it is easier to implement a spam filtering system or other real-time tracking system.

9.Pub/Sub

Maintaining the user's mapping of data in updates is a common task in the system. Redis's pub/sub feature uses the SUBSCRIBE, UNSUBSCRIBE, and PUBLISH commands to make this easier.

10. Queue

Queues can be seen everywhere in current programming. In addition to commands of push and pop types, Redis also has commands that block queues, allowing one program to be added to the queue by another program when it is executed. You can also do something more interesting, such as a RSS feed queue for rotating updates.

11. Caching

Redis caching is used in the same way as memcache.

Web applications can't fight model wars endlessly. Look at these Redis primitive commands, which are simple but powerful, and what can be accomplished by combining them is even more unimaginable. Of course, you can write code to do all of this, but Redis is obviously easier to implement.

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