title: "Redis Data Structure" description: "Redis数据结据" tags:

  • redis

Docs

https://github.com/redis/redis-doc/blob/master/topics/data-types-intro.md

https://github.com/redis/redis-doc/blob/master/topics/data-types.md

Learning Test Env

docker run --rm -dt --name learning redis:5.0.9 redis-cli && docker exec -it learning redis-cli

Note

  1. About key
  • KEY设置太长不是一件好事，如大于1024byte，对于内存及寻找都会有影响，建议可以用SHA1压缩
  • KEY设置太短不是一件好事，因为可读性会变低
  • KEY的最大值为512MB
  1. About creation and removal of keys
  • 当添加值到不存在键中，添加时会创建一个相应数据结构
  • 当删除值使键中数据类型为空，键会自动销毁，Stream除外
  • 调用如LLEN空键只读命令或删除命令，总返回与空链一致结果
127.0.0.1:6379> get a
(nil)
127.0.0.1:6379> lpush a a
(integer) 1
127.0.0.1:6379> get a
(error) WRONGTYPE Operation against a key holding the wrong kind of value
127.0.0.1:6379> lpop a
"a"
127.0.0.1:6379> get a
(nil)

Commands

  • EXISTS KEY [KEY ...]
  • TYPE KEY
  • DEL KEY [KEY ...]
  • EXPIRE KEY SECONDS
  • TTL KEY
  • PEXPIRE KEY MILLISECONDS
  • PTTL KEY
  • PERSIST KEY
127.0.0.1:6379> set ex a
OK
127.0.0.1:6379> del ne
(integer) 0
127.0.0.1:6379> type ex
string
127.0.0.1:6379> type ne
none
127.0.0.1:6379> exists ex
(integer) 1
127.0.0.1:6379> exists ne
(integer) 0
127.0.0.1:6379> del ex
(integer) 1
127.0.0.1:6379> del ne
(integer) 0
127.0.0.1:6379> set ep a
OK
127.0.0.1:6379> expire ep 5
(integer) 1
127.0.0.1:6379> get ep
"a"
127.0.0.1:6379> get ep
(nil)
127.0.0.1:6379> set ep a
OK
127.0.0.1:6379> expire ep 100
(integer) 1
127.0.0.1:6379> ttl ep
(integer) 97
127.0.0.1:6379> pttl ep
(integer) 82937
127.0.0.1:6379> persist ep
(integer) 1
127.0.0.1:6379> persist ep
(integer) 0
127.0.0.1:6379> pttl ep
(integer) -1
127.0.0.1:6379> ttl ep
(integer) -1

String

Binary-safe strings.

Note

  • About value

    • VALUE最大值为512MB

Commands

  • SET KEY VALUE [expiration EX seconds|PX milliseconds] [NX|XX]
  • GET KEY
  • INCR KEY
  • INCRBY KEY INCREMENT
  • DECR KEY
  • DECRBY KEY DECREMENT
  • MSET KEY VALUE [KEY VALUE ...]
  • MGET KEY [KEY ...]
127.0.0.1:6379> set t1 1
OK
127.0.0.1:6379> get t1
"1"
127.0.0.1:6379> incr t2
(integer) 1
127.0.0.1:6379> incrby t2 10
(integer) 11
127.0.0.1:6379> decr t2
(integer) 10
127.0.0.1:6379> decrby t2 10
(integer) 0
127.0.0.1:6379> decr t2
(integer) -1
127.0.0.1:6379> incr t1
(integer) 2
127.0.0.1:6379> get t1
"2"
127.0.0.1:6379> set t3 a
OK
127.0.0.1:6379> incr t3
(error) ERR value is not an integer or out of range
127.0.0.1:6379> mset t4 1 t5 b
OK
127.0.0.1:6379> mget t4 t5 t6
1) "1"
2) "b"
3) (nil)
127.0.0.1:6379> set t7 c nx
OK
127.0.0.1:6379> set t8 c xx
(nil)
127.0.0.1:6379> mget t7 t8
1) "c"
2) (nil)

List

collections of string elements sorted according to the order of insertion. They are basically linked lists.

Note

  • 内部车现为链表结构

Commands

  • LPUSH KEY VALUE [VALUE ...]
  • RPUSH KEY VALUE [VALUE ...]
  • LRANGE KEY START STOP
  • LTRIM KEY START STOP
  • LPOP KEY
  • RPOP KEY
  • BLPOP KEY [KEY ...] TIMEOUT
  • BRPOP KEY [KEY ...] TIMEOUT
  • LLEN KEY
127.0.0.1:6379> lpush tl 1 2 3 4 a b c d
(integer) 8
127.0.0.1:6379> rpush tl q w e r 5 6 7 8
(integer) 16
127.0.0.1:6379> lrange tl 0 -1
 1) "d"
 2) "c"
 3) "b"
 4) "a"
 5) "4"
 6) "3"
 7) "2"
 8) "1"
 9) "q"
10) "w"
11) "e"
12) "r"
13) "5"
14) "6"
15) "7"
16) "8"
127.0.0.1:6379> ltrim tl 1 -2
OK
127.0.0.1:6379> lrange tl 0 -1
 1) "c"
 2) "b"
 3) "a"
 4) "4"
 5) "3"
 6) "2"
 7) "1"
 8) "q"
 9) "w"
10) "e"
11) "r"
12) "5"
13) "6"
14) "7"
127.0.0.1:6379> lpop tl
"c"
127.0.0.1:6379> rpop tl
"7"
127.0.0.1:6379> lrange tl 0 -1
 1) "b"
 2) "a"
 3) "4"
 4) "3"
 5) "2"
 6) "1"
 7) "q"
 8) "w"
 9) "e"
10) "r"
11) "5"
12) "6"
127.0.0.1:6379> del tl
(integer) 1
127.0.0.1:6379> lrange tl 0 -1
(empty list or set)
127.0.0.1:6379> blpop tl 1
(nil)
(1.00s)
127.0.0.1:6379> blpop tl 10
1) "tl"
2) "10"
(8.31s)
127.0.0.1:6379> brpop tl ne 10
1) "tl"
2) "ee"
(5.93s)
127.0.0.1:6379> brpop tl ne 10
1) "tl"
2) "e2"
127.0.0.1:6379> lpush tl 1 2 3
127.0.0.1:6379> llen tl
(integer) 3

Set

collections of unique, unsorted string elements.

Sorted Set

similar to Sets but where every string element is associated to a floating number value, called score. The elements are always taken sorted by their score, so unlike Sets it is possible to retrieve a range of elements (for example you may ask: give me the top 10, or the bottom 10).

Hashe

which are maps composed of fields associated with values. Both the field and the value are strings. This is very similar to Ruby or Python hashes.

Bit Array

it is possible, using special commands, to handle String values like an array of bits: you can set and clear individual bits, count all the bits set to 1, find the first set or unset bit, and so forth.

HyperLogLogs

this is a probabilistic data structure which is used in order to estimate the cardinality of a set. Don't be scared, it is simpler than it seems... See later in the HyperLogLog section of this tutorial.

Streams

append-only collections of map-like entries that provide an abstract log data type. They are covered in depth in the Introduction to Redis Streams.