The related knowledge of memory database Redis is almost a must-test question for major manufacturers. Below I summarize the 11 interview questions for designing Redis:
- Tell me about the basic data types of Redis
- Why is Redis fast?
- So why did you switch to multithreading after Redis 6.0?
- Do you know what a hot key is? How to solve the hot key problem?
- What is cache breakdown, cache penetration, and cache avalanche?
- What are the expiration strategies of Redis?
- So what should I do if the expired keys are not deleted regularly + lazily?
- What are the persistence methods? What's the difference?
- How to achieve high availability of Redis?
- Can you talk about the principle of redis cluster?
- Do you understand the Redis transaction mechanism?
Why do we have to use Redis?
Fast speed, completely based on memory, implemented in C language, network layer uses epoll to solve high concurrency problems, single-threaded model avoids unnecessary context switching and competition conditions;
Note: Single thread only means that one request is used to process the client's request on the network request module. If it is persisted, a thread/process will be reopened for processing.
Rich data types. Redis has 8 data types. Of course, the five commonly used types are String, Hash, List, Set, and SortSet. They all organize data based on key values. Each data type provides a very rich operation command, which can meet most of the needs. If you have special needs, you can create new commands yourself through the lua script.
However, for the use of Redis, I believe that there are still many people who don’t know how to use Redis, and many small and medium-sized enterprises have not yet used Redis. However, the current requirements of large companies require the use of Redis to be proficient and mastered. Therefore, learn Redis has no time to delay.
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First, the last set of Redis mind maps
This set of Redis mind maps is still very detailed and specific, with a lot of content. The pictures show the "simple version". In fact, there is more complete content. The "+" button is not expanded, and the Redis mind map can be more Good to help us understand the content of this notebook, and also let us have a clearer thinking when learning Redis.
Redis mind map content:
- Basic data structure and its application: string + list + set + ordered set + hash
- Implement distributed locks with Redis
- Persistence: AOF+RDB
- How to solve the multi-threaded competition problem
- Database and cache double write inconsistency
- Affairs
- How to ensure high availability
- sentinel
- Cluster
- Interview questions related
Then, go to the main dish: Redis technical notes
1. Know Redis (Introduction to Redis + Introduction to Redis Data Structure)
2. Use Redis to build web applications (login and cookie cache + use Redis to implement shopping cart + web page cache + data line cache + web page analysis)
3. Redis commands (string + list + collection + hash + ordered collection + publish and subscribe + other commands)
4. Data security and performance assurance (persistence options + replication + processing system failures + Redis transactions + non-transactional pipeline + notes on performance)
5. Use Redis to build support programs (use Redis to record diary + counters and statistics + find the city and country of the IP + service discovery and configuration)
6. Use Redis to build application components (auto-completion + distributed lock + counting semaphore + task queue + message pull + use Redis for file distribution)
7. Search-based applications (using Redis for search + ordered index + advertising targeting + job search)
8. Build a simple social networking site (user and status + homepage timeline + follower list and following list + status message publishing and deletion + streaming API)
9. Reduce memory usage (short structure + fragmented structure + packed storage binary bit byte)
10. Expand Redis (expand read performance + expand write performance and memory capacity + expand complex queries)
11. Redis Lua script programming (add new functions without writing C code + use Lua to rewrite locks and semaphores + remove WATCH/MULTI/EXEC transactions + use Lua to fragment the list)
Finally, Redis interview questions should also have
1. Why use redis? /Why use cache?
2. Why use redis instead of map/guava for caching?
3. The difference between redis and memcached
4. Redis common data structure and usage scenario analysis
5.redis set expiration time
6. Redis memory elimination mechanism (There are 2000w data in MySQL and only 20w data in Redis. How to ensure that the databases in Redis are hot data?)
7. Redis persistence mechanism (how to ensure that the data can be restored after redis hangs and restarts?)
8.redis transaction
9. Redis common exceptions and solutions
10. Common application scenarios in a distributed environment
11.Redis cluster mode
12. How to solve the key problem of concurrent competition in Redis?
13. How to ensure the data consistency when the cache and the database are double-written?
More BATJM and other major Redis interview questions (108 questions):
to sum up
First, reading can improve programming skills . Learning starts with imitation. Whether it is reading the sample code in the tutorial when you are getting started, or reading the source code of excellent projects when you are advanced, it is a good way to learn.
Secondly, reading can improve debug ability . Only by practicing the accumulated ability to read the code can you understand the code and locate the problem in the code quickly and accurately.
This Redis technical note is highly recommended for you to study, the download amount can explain all the problems, and it can also be shared with friends in need for free!
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