Redis three kinds of special data types

Redis three kinds of special data types

Bitmap

BitmapIs through a bitto represent an element or a value corresponding to the status bits

Wherein the key is the corresponding element itself, but also by the fact underlying the operation of the character string to achieve

RedisFrom the 2.2new version after the setbit, getbit, bitcountand several other bitmap related commands

Although the new command, but are themselves operating on a string

SETBIT key offset value

Which offsetmust be a number, value can only be a 0or1

This command return value is the value before the modification

For example, call

setbit byte0 0 1;
setbit byte0 2 1;
setbit byte0 5 1;
​
setbit byte1 1 1;
setbit byte1 4 1;

Corresponding to the value of the memory is such

byte	bit0	bit1	bit2	bit3	bit4	bit5	bit6	bit7
byte0	1	0	1	0	0	1	0	0
byte1	0	1	0	0	1	0	0	0

 

You can see bitthe default value is 0then Bitmapused in the actual development of it?

To give an example: store user online

Here only one key, and then as a user ID offset, if it is set to online 1, offline is set to0

// Set online 
$ redis-> Online setBit 0 1 ; 
// set offline 
$ redis-> setBit Online 0 0 ; 
// get the state 
$ redis-> GETBIT Online 0 ; 
// get the number of online 
$ redis -> bitCount online;

Geo

RedisThe GEOproperties in Redis 3.2the launch version

This function can be given by the user location information is stored, and the operation information

GEO data structure There are six command

• geoadd

• geopos

• geodist

• georadius

• georadiusbymember

• geohash

GEOADD

GEOADD key longitude latitude member [longitude latitude member ...]

Given spatial elements (latitude, longitude, name) added to the specified key inside

These data will be zseta structure which is stored in the key

Such as setting

keyIs Sicily(islands in Assisi, Italy)

member1As Palermo(the Sicilian regional capital Palermo, Italy)

member2As Catania(the capital of Italy Sicily Province of Catania Catania)

redis> GEOADD Sicily 13.361389 38.115556 "Palermo" 15.087269 37.502669 "Catania"
(integer) 2

GEOPOS

GEOPOS key member [member ...]

Returns all elements from a given position inside the key position (longitude and latitude)

For example, callGEOPOS Sicily Palermo

Returns the Palermolatitude and longitude

redis> GEOPOS Sicily Palermo
1) 1) "13.361389338970184"
2) "38.115556395496299"

GEODIST

GEODIST key member1 member2 [unit]

Returns the given distance between the two positions

If a location between the two does not exist, then returnnull

Parameter specifies the units unitmust be in the following units wherein a default :( m)

• m Meter

• km km

• mi mile

• ft foot

For example, callGEODIST Sicily Palermo Catania

Return Palermoand Cataniadistance166274.15米

redis> GEODIST Sicily Palermo Catania
"166274.15156960039"

GEORADIUS

GEORADIUS key longitude latitude radius m|km|ft|mi [WITHCOORD] [WITHDIST] [WITHHASH] [ASC|DESC] [COUNT count]

A given latitude and longitude as the center, from the position of the element which contains the return key, the center does not exceed a given maximum distance elements in all positions

Consistent distance units and above, where the latter option:

• WITHDIST

  While the return position of the element, the distance between the center position of the elements is also returned together

  User distance units and given range consistent units

• WITHCOORD

  The latitude and longitude position of the element is also returned together

• WITHHASH

  In 52bit signed integer form of the element after the original return position geohash encoded ordered set value

  This option is mainly used for debugging or underlying application, the actual effect is not large in

For example, callGEORADIUS Sicily 15 37 200 km WITHDIST

It means that the return keyis Sicilyin in

To 经度15, 纬度37as the center, the radius of 200kmthe elements within the circular range, and the distance to the center element

redis> GEORADIUS Sicily 15 37 200 km WITHDIST
1) 1) "Palermo"
 2) "190.4424"
2) 1) "Catania"
 2) "56.4413"

HyperLogLog

Redis Cardinality statistics

This structure can be very provincial statistics to various counts of memory, such as 注册 IP 数, 每日访问 IP 数, 页面实时UV, 在线用户数etc.

But it also has its limitations, is only the number of statistics, and no way to know what specific content

PFADD

Redis> PFADD Databases "Redis" "MongoDB" "MySQL" 
(Integer) 1 
Redis > PFADD Databases "Redis"   # Redis already exists, do not have to update the estimate of the number 
(Integer) 0

PFCOUNT

redis> PFCOUNT databases
(integer) 3

PFMERGE

PFMERGE achievement sourcekey [sourcekey ...]

Multiple HyperLogLogmerge into oneHyperLogLog

The combined HyperLogLogbase close to all inputs HyperLogLogof可见集合的并集

The combined results of HyperLogLogwill be stored in the destkeykey inside

If the key does not exist, then the command before execution, will create a space for the key HyperLogLog

redis> PFADD nosql "Redis" "MongoDB" "Memcached"
(integer) 1
redis> PFADD RDBMS "MySQL" "MSSQL" "PostgreSQL"
(integer) 1
redis> PFMERGE databases nosql RDBMS
OK
redis> PFCOUNT databases
(integer) 6