Value/string in redis

String 

help set

nx yes key Value does not appear , Before setting （ For distributed locks ）

xx yes key There must have been , Before setting , Equivalent to updating

mset You can set multiple key

mset k1 a k2 b

mget k1 k2 

APPEND Can increase value Value

APPEND k1 "word"

get k1

GETRANGE Where to go and where to end , And display

GETRANGE k1 2 3

GETRANGE k1 2 -1 from 2 To the last

GETRANGE k1 2 -2 from 2 To the next to last

SETRANGE Where to cover

SETRANGE k1 6 666 From 6 Cover... On positions 666

STRLEN Display length

STRLEN k1  Show k1 length

The number  

type k1 see k1 The type of

OBJECT encoding k1

key There is type, describe value Properties of

key There is encoding, see value code

INCR k1        k1 Add one

INCRBY k1 value        k1 Add value

DECR k1        k1 Minus one

DECR k1 value        k1 reduce value

INCRBYFLOAT k1 0.5        k1 Add 0.5

Binary security

Character stream

Byte stream

redis When a process interacts with the outside world , Get the byte stream

redis-cli --raw

raw： If not raw,redis Only recognize ascii, exceed ascii, It will be displayed in hexadecimal , add raw, It will trigger the format of the code set

GETSET： Take out the old value , Insert new values

GETSET k1 666        return k1 The value of the original

get k1        Returns the new value

MSETNX： Only k It can only be set when it does not exist , You can set multiple key value

Principle operation ： One addition failed , The rest failed

bitmap Bitmap

setbit key offset value： hold key Corresponding value, The number on the bit number becomes value

offset It's an array of bits, not bytes , Is the binary offset （1 Bytes are 8 Binary bits ）

0 1 2 3 4 5 6 7 8 9 10 11 12

0-7 Represents the first byte         8-16 Represents the second byte

bitpos key bit [start] [end]： Within the specified byte index range （start end）, stay key Corresponding value in , The first occurrence on the binary bit bit The location of

bitcount key [satrt end]：  Within the specified byte index range （start end）, stay key Corresponding value in , Statistics 1 Several times

BIIOP operation destkey key [key...]：operation（and or xor not） The result returned key key1 And key2 do operation operation