| Redis is an open source log-type, key-value database written in ANSI C language, supports network, can be memory-based and persistent, and provides APIs in multiple languages. Since March 15, 2010, the development of Redis has been hosted by VMware. Since May 2013, the development of Redis has been sponsored by Pivotal. |
1. Install Redis
Redis configuration file: /etc/redis.conf
Redis main program: /usr/bin/redis-server
Client Tools: /usr/bin/redis-cli
Default listening port: 6379
Data directory: /var/lib/redis
Service script: /usr/lib/systemd/system/redis.service
yum install redis # epel source based on CentOS 7
2. Connect to Redis
The client command tool for Redis is redis-cli, which connects to the local Redis service by default.
If you need to connect remotely, use redis-cli -h HOST -p PORT -a PASSWD
[root@cache1 ~]# redis-cli 127.0.0.1:6379> ping # Use the ping command to test connectivity to the service PONG # The server replies to pong, indicating that there is no problem with the network connection
3. Redis data type
String (string)
String is the most basic type of redis, you can understand it as the exact same type as Memcached, a key corresponds to a value.
The string type is binary safe. Means redis string can contain any data. Such as jpg images or serialized objects.
The string type is the most basic data type of Redis, and a key can store a maximum of 512MB.
Hash
Redis hash is a set of key-value (key=>value) pairs.
Redis hash is a mapping table of field and value of string type, and hash is especially suitable for storing objects.
List
Redis lists are simple lists of strings, sorted by insertion order. You can add an element to the head (left) or tail (right) of the list.
Set
Redis's Set is an unordered collection of string type.
Sets are implemented through hash tables, so adding, deleting, and searching are all O(1).
zset (sorted set: sorted set)
Redis zset, like set, is also a collection of elements of type string, and does not allow duplicate members.
The difference is that each element is associated with a fraction of type double. Redis sorts the members of the set from small to large through scores.
The members of zset are unique, but the score can be repeated.
4. Get help
help @ + double-click the tab # Double-click the tab will appear help for various subcommands help @string # String related configuration help @list # list related configuration; lists are like arrays help @set help @hash ......
Five, List related commands
Several other data types are relatively simple, and the use of commands can be obtained through help. The easiest way is Baidu. Since it is difficult to understand some operations of List-related commands just by looking at the help, I will take them out and talk about the most commonly used commands separately.
Example:
127.0.0.1:6379> LPUSH stu aubin # LPUSH, add elements to the left of the list, the list does not exist and is automatically created (integer) 1 127.0.0.1:6379> RPUSH stu 22 # RPUSH, add elements to the right of the list, if the list does not exist, it will be created automatically (integer) 2 127.0.0.1:6379> RPUSHX stu nan # RPUSHX, if the list exists, add elements to the right (integer) 3 127.0.0.1:6379> LPUSHX stu linux # LPUSHX, add elements to the left if the list exists (integer) 4 127.0.0.1:6379> LRANGE stu 0 10 # LRANGE, display 0-10 values of a list named stu 1) "aubin" 2) "22" 3) "nan" 4) "linux" LPOP stu # Left pop, delete the first element in the list named stu RPOP stu # pop right, delete the last element in the list named stu LREM stu 3 aubin # delete 3 elements whose value is aubin from the beginning to the end LREM stu -3 aubin # delete 3 elements whose value is aubin from the end to the beginning LREM stu 0 aubin # remove all elements whose value is aubin
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