[video of Teacher Zhao Yuqiang's speech on wot] redis high performance cache and persistence

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【 Teacher zhaoyuqiang is here WOT Video of the speech on 】Redis High performance cache and persistence

 

What is? Redis？

Redis It's a key-value The storage system . and Memcached similar , It supports storage value There are more types , Include string( character string )、list( Linked list )、set( aggregate )、zset(sorted set -- Ordered set ) and hash（ Hash type ）. And Memcached equally , To ensure efficiency , The data is cached in memory . The difference is redis Periodically, updated data is written to disk or changes are written to an appended log file , And on this basis to achieve master-slave( Master-slave ) Sync .

Redis Is a high-performance key-value database .Redis Appearance , A lot of compensation memcached This kind of key/value Insufficient storage , In some cases, it can play a very good complementary role to the relational database . It provides many ways （ Such as Java and C） client , Easy to use .

Redis Support master-slave synchronization . Data can be synchronized from the master server to any number of slaves , A slave server can be the master server associated with other slaves .

Redis And MemCached The difference between

• Redis and Memcache It's all about storing data in memory , It's all memory databases . however memcache It can also be used to cache other things , For example, pictures 、 Video and so on ;

• Redis It's not just about supporting simple k/v Data of type , It also provides list,set,hash Such as data structure storage ;

• Virtual memory ：Redis When physical memory runs out , You can use something that hasn't been used for a long time value Swap to disk ;

• Expiration strategy ：memcache stay set When it comes to , for example set key1 0 0 8, Never expire .Redis It can be done by, for example expire Set up , for example expire name 10;

• Distributed ： Set up memcache colony , utilize magent Be one master and many followers ;redis You can be a master and a slave . You can have one master and one slave ;

• Storage data security ：memcache After hanging up , The data is gone ;redis Can be saved to disk on a regular basis （ Persistence ）;

• disaster recovery ：memcache After hanging up , Data is not recoverable ; redis Data can be lost through aof recovery ;

• Redis Support data backup , namely master-slave Mode data backup ;

• The application scenarios are different ：Redis Come out as NoSQL Database use outside , It can also be used as a message queue 、 Data stack, data cache, etc ;Memcached Suitable for caching SQL sentence 、 Data sets 、 User temporary data 、 Delay querying data and session etc. .