Redis special data type usage scenarios

BitMaps 

Is a memory saving data structure ..0,1 Similar to boolean type

Hyperlogloss

Redis HyperLogLog It's an algorithm for cardinality statistics ,HyperLogLog The advantages of , When the number or volume of input elements is very, very large , The space needed to calculate the cardinality is always fixed Of 、 And it's very small .

stay Redis Inside , Every HyperLogLog Keys only cost 12 KB Memory , So we can calculate the proximity 2^64 A base of different elements Count . This is the same as calculating the cardinality , The more elements consume memory, the more collections there are .

Use a small amount of memory , Store a lot of data ... The statistical results have errors ..

Web browsing statistics , The number of visits and so on do not particularly need accurate data , You can use it .

Streams

Publish subscribe

Redis Publish subscribe (pub/sub) It's a message communication mode ： sender (pub) Send a message , subscriber (sub) receive messages .

Redis Clients can subscribe to any number of channels .