One : redis is an open source, written in C language, supports network, can be based on memory and can also be persistent, log type, key-value storage nosql database. As a cache server, the speed and efficiency are very fast, similar to memcache
Data types supported by redis : string string type, list linked list type, set unordered collection type, zset ordered collection type and hash hash type
Redis supports main memory synchronization. Data can be synchronized from the master server to any number of slave servers. Similarly, the slave server can also be used as the master server associated with other slave servers.
two:
Operate redis data types on linux
(1) Sting type
set key value
get key to get the corresponding value
(2) List type:
lpush key values
lpush list1 1 2 3 4 5
The data structure of the stack is first in last out (last in first out)
lpush means that the stack operation is performed from the left, and the order of the data taken out is exactly the opposite of the order in which it is pushed into the stack.
rpush means that the stack operation starts from the far right, and the order in which the data is taken out is the same as the order in which the data is inserted.
A key in the set can correspond to multiple value values, which are stored based on linked lists
lrange key 0 -1
lrange list1
get the result:
5
4.
3.
2.
1
(3) set unordered collection
The set collection does not allow duplicate elements, if there are duplicates, the duplicate data will be automatically deleted
Stored value: sadd key values
Example: sadd list2 abc
Value: smembers key
Example: smembers list2
The retrieved data is an unordered collection, with no duplicate data
(4) zset collection: there is order and cannot be repeated
The number when inserting data will be used as the basis for sorting, and the default is in ascending order.
Stored value: by default, it is sorted in ascending order by score
zset key score1 value1 score2 value2 score3 value3
Value; the retrieved data is an ordered set with no repetition in ascending order
zrange key 0 -1 ascending output
zrevrange key 0 -1 descending order output
delete: zrem key value
Three: expiration time in redis
Set expiration time: expire key time
Check how long it expires: ttl key
