foreword
Accept the suggestion of Brother Xu Zhu, and a series of articles on redis will be published in the future
This article explains the operations with high utilization rate of Redis7 data types. For all operations of Redis7 data types, please refer to: Commands | Redis
Previous article: Getting to know redis [installation, use and uninstallation of redis]_Work hard and work hard mlx's blog-CSDN blog
If you have any questions, you can private message me anytime~
Table of contents
Redis ordered collection Zset (sorted set)
Redis cardinality statistics (HyperLogLog)
redis key (key)
A list of commonly used redis commands:
The detailed introduction of common commands for keys is as follows:
keys * #View all keys in the current k= library
exists key #Judge whether a certain key exists (in redis instructions, 0 means that 0 instructions are queried (the instruction that meets the conditions cannot be found), and 1 means that the query is successful)
type key #View the data type of the current key
del key #Delete the specified key
unlink key #Non-blocking delete, just delete keys from the keyspace metadata, no real deletion will be performed in subsequent asynchronous operations, at present we only need to have a certain impression of this command, and we will further introduce it later
ttl key #Check how many seconds the key we queried has expired -1 means it will never expire -2 means it has expired
expire key seconds #Set the expiration time for the key
move key [0-15] #Move the key of the current database to the specified database, redis has 16 databases by default
select [0-15] #Switch database [0-15], the default is 0, the subscript exceeds 0 A range of -15 will report an error
dbsize # View the number of keys in the current database
flushdb #Empty the current library, use with caution
flushall #Empty 16 databases with cautionConsidering that this operation is very dangerous, I will not demonstrate it here.
help @ type to view a type of help documentation
Notes: The instructions we operate are not case-sensitive, but the keys we manually set are case-sensitive
redis string (String)
String is the most basic data type in redis. A key corresponds to a value. String data is binary safe, which means it can store any data, including jpg files and
Common instructions in String:
The detailed introduction to the String type command is as follows:
set key value
get key # Get the value corresponding to the specified key
mset [key1] [value1] [key2] [value2] [key3] [value3] #Set one or more key-value pairs at the same time
mget [key1] [key2] [key3] #Get the values of multiple keys at the same time
msetnx [key1] [value1] [key2] [value2] #Set one or more key-value pairs at the same time. It must be ensured that none of the keys exists to succeed
Get the specified interval
getrange [key] 0 -1 # Get all the values of this key
getrange [key] 0 3 # Get the value of this key between index 0 and index 2
getrange [key] 1 xxx #Set the range of the specified interval the value within
Value increase or decrease
incr [key] # increment number +1
incr [key] [increment] # increase the specified integer +increment
decr [key] # decrease the number -1
decr [key] [increment] # decrease the specified integer -increment
Get the length of the string and add the content
strlen [key] # Get the length of the value corresponding to the key
append [key] [vale] #add string content
distributed lock
setex [key] [expiration time] [value] # set the key with expiration time, dynamic setting
setnx [key] [value] # Set the value of the key only when the key does not exist.
set [key] [value] get # Set the value of the given key to value and return the old value of the key
getset [key] [value] # Set the value of the given key to value and return the old value of the key
Application Scenarios:
1. Douyin likes
2. Like the article
Redis list (List)
Introduction to list
The structure of a double-ended linked list, the capacity is 2 to the 32nd power minus 1 element, about more than 4 billion, the main functions include push/pop, etc., generally used in stacks, queues, message queues and other scenarios. The list corresponds to a single key with multiple values
Both left and right can be inserted and added;
If the key does not exist, create a new linked list;
If the key already exists, add the content;
If all values are removed, the corresponding keys disappear.
- The bottom layer of its list is actually a doubly linked list, which has high performance on both ends of the operation, and the performance of nodes in the middle through index subscript operations will be poor.
of- li; common operations of list
A common introduction to list operations
lpush [key] [value] ... // Put elements into the head (left) of the list
rpush [key] [value] ... // put elements into the list (right)
lrange [key] 0 -1 // Traversing the list from the left can only traverse from the left
lpop [key] // The leftmost stack is the first one traversed by lrange
rpop [key] // The rightmost stack is the last one traversed by lrange
lindex [key] [index] // Get the value by index value
llen [key] // Get the number of elements
lrem [key] [num] [value] // delete num value value from left to right
lrem [key] 0 [value] // Delete all values that are valued from left to right
ltrim [key] [start] [end] // intercept the value in the specified range and then assign it to [key], that is, delete the value outside this range
rpoplpush [key1] [key2] [value] //Remove the last element of the list, and add this element to the first of another list and return
lset [key] [index] [value] //Change the index value of key to value
linsert [key] brfore/after [value1] [value2] // Add a specific value before and after an existing value in the list
Application Scenario
WeChat official account pushes me to subscribe to the author's articlesWhen the author I subscribed publishes two new articles, the corresponding ids are 11 and 22 respectively
lpush likearticle:ljl 11 22
I want to view the first ten subscribed article information:
lrange likearticle:ljl 0 9
Redis hash (Hash)
brief introduction
When we talk about hashing, our first reaction must be hashmap in java. The hash in redis is similar to the hash in java, the kv mode remains unchanged, but v is a key-value pair => Map<String,Map<Object,Object>
List of common commands
Commonly used commands in detail
hset/hget/hmset/hmget/hgetall/hdel //hset/get corresponds to get value and get value hmset/hmget is to get and get multiple values hgetall is to get all values hdel is to delete a value
hlen // Get all the quantities in a key
hexists [key] [k1] // see if there is a key k1 in the key
hkeys [key] // Get all the keys in the key
hvals [key] // Get all the values in the key
hincrby [key] k1 [num] // The value of k1 in the key increases by num integer
hincrbyfloat [key] k1 [num] // The value of k1 in the key increases by num decimals
hsetnx [key] k1 [value] // There is no assignment, there is invalid
Typical application scenarios of hash:
Early adoption of the shopping cart
Redis collection (Set)
brief introduction
When we think of set, the first thing we think of is hashset in java, and set collection in redis. The values in set must not be repeated. The way he stores data is single value and multiple values.
common command
Detailed introduction of commonly used commands
SADD key member ... // add element
SMEMBERS key // traverse all elements in the collection
SISMEMBER key member // determine whether an element is in the set
SREM key member ... // delete element
SCARD key // Get the collection length
SRANDMEMBER key m // Randomly select m from the set collection If it exceeds the maximum number, all will be taken outIf the written value is a negative number, such as -3, it means that 3 need to be taken out, but there may be duplicate values that will not be deleted
SPOP key m // Randomly pop an element from the collection, remove one and delete one
SMOVE key1 key2 an existing value in key1 // Assign an existing value of key1 to key2
set operation
SDIFF keyA keyB // A - B is a collection of elements that belong to A but not to B
SUNION keyA keyB // AUB is the merged collection of elements belonging to A or B
SINTER keyA keyB // A ∩ B belongs to both A and B
SINTERCARD numkeys keyA keyB [LIMIT limit] // It also seeks intersection, does not return the result set, only returns the cardinality of the result limit is used to limit the cardinality of the intersection, if the result exceeds the limited number of limit during the operation, it returns directly
Typical Application Scenarios
1. vx lottery
2. Vx circle of friends set like friends
3. Tweet people you may know in QQ
Redis ordered collection Zset (sorted set)
Introduction to zset
Zset adds a field such as score on the basis of set. It is precisely because of this field that zset can sort elements on the basis of satisfying the characteristics of set
Commonly used instructions about zset
Detailed introduction to zset common commands
ZADD key score member [ score member ] // add element
ZRANGE key start stop [WITHSCORES] // Return the order of element scores from small to large Return all elements with indexes from start to stop
ZREVRANGE key 0 - 1 [WITHSCORES] // reverse order
ZRANGEBYSCORE key min max [WITHSCORES] [LIMIT offset count] // Get the elements of the specified score range (min, max) excluding limit is the return limit, how many to return
ZSCORE key member // Get the score of the element
ZCARD key // Get the number of elements in the collection
ZREM key The value corresponding to a certain score // delete the element
ZINCRBY key increment member // increase the score of an element
ZCOUNT key min max // Get the number of elements within the specified score range
ZMPOP numkeys key [key …] <MIN | MAX> [COUNT count] // Pop one or more keys from the first non-empty sorted set in the key name list, which are member-score pairs
ZRANK key values value // get subscript value
ZREVRANK key values // Obtain subscript values in reverse order
Application scenario:
Sort products according to their sales volume
Redis bitmap (bitmap)
The concept of bitmap
Description: A statistical binary state data type implemented with the String type as the underlying data structure
A bitmap is essentially an array , which is a bitwise operation based on the String data type. The array consists of bits, each of which corresponds to an offset (we call it an index). The maximum number of bits supported by Bitmap is 2^32 bits, which can greatly save storage space. Using 512M memory, it can store up to 4.29 billion bytes of information (2^32 = 4294967296)
List of common commands
Commonly used commands in detail
SETBIT key offset value // Set the value of the first offset to value, value can only be 0 or 1, offset starts from 0
GETBIT key offset // Get the value of the offset bit
STRLEN key // Find out how many bytes are more than 8 bits, and then expand the capacity according to 8 bits per byte
BITCOUNT key // Find out how many 1s are contained in the key
BITOP and destKey key1 key2 // Do a logical union of one or more keys and save the result to destkey
The following operations are the same, and will not be repeated here~BITOP or destKey key1 key2 // Do logical OR for one or more keys, and save the result to destkey
BITOP XOR destKey key1 key2 // Do logical XOR for one or more keys, and save the result to destkey
BITOP NOT destKey key1 key2 // Do logic NOT for one or more keys, and save the result to destkeyTypical application scenario:
the application scenario of sign-in is very suitable for bitmap365 days a year, how many days are signed in every day?
by year
Redis cardinality statistics (HyperLogLog)
basic introduction
The cardinality estimation algorithm of the deduplication statistics function is HyperLogLog, and the cardinality is the real number of a data set after deduplication. Cardinality statistics are used to count the number of unique elements in a collection, that is, the calculation of the remaining elements after deduplication of the collection only needs to spend memory, and can record the cardinality of 2 to the 64th power = 18446744073709551616 different elements. However, because HyperLogLog only calculates the cardinality based on the input elements and does not store the input elements themselves, HyperLogLog cannot return the individual elements of the input like a set.
common command
pfadd hyl1 1 1 1 1 2 3 6
pfadd hyl2 2 4 4 4 6 7 8 9
pfcount hyl2 //Calculate the number of elements in hyl2 after deduplication
pfmerge distResult hyl2 hyl1 //Merge the elements in hyl2 and hyl1 and deduplicate
pfcount disResult / /Calculate the number of elements after deduplication in hyl2
Application Scenario
Tmall website homepage billion level UV redis statistical scheme
Redis Geospatial (GEO)
brief introduction
The geographic location on the earth is represented by two-dimensional latitude and longitude, longitude range (-180, 180], latitude range (-90, 90], as long as we determine the latitude and longitude of a point, we can obtain its position on the earth.
For example, Didi Taxi, the most intuitive operation is to record and update the location of each car in real time.
Then when we want to find a car, we search the database for the latitude and longitude of the vehicle within r kilometers from us (coordinates x0, y0) and
copy it directly on the map. : pick coordinate system
common command
Commonly used designation details
GEOADD city 116.403963 39.915119 "Tiananmen" 116.403414 39.924091 "Forbidden City" //GEOADD adds latitude and longitude coordinates
ZRANGE city 0 -1 // View (Chinese garbled characters will appear)
redis -cli -a 111111 -p 6379 -- raw // Solve Chinese garbled characters
GEOPOS city Tiananmen Forbidden City // GEOPOS returns the latitude and longitude
// GEOHASH returns the geohash representation of the coordinates (base32 encoding)
GEOHASH city Tiananmen Forbidden City
//GEODIST returns the distance between two locations (m km )
GEODIST city Tiananmen Great Wall km
//GEORADIUS takes the given latitude and longitude as the center, returns the location elements contained in the key, and the distance from the center does not exceed the given maximum distance All positional elements.
GEORADIUS city 116.418017 39.9144444 10 km withdist withcoord count 10 desc
//GEORADIUSBYMEMBER Find the elements within the specified range, the center point is determined by the given position element
GEORADIUsbymember city Tiananmen 10 km withdist withcoord count 10 withhashApplication Scenario
- Restaurants and hotels near Meituan
- Stores near Gaode map
Redis style (Stream)
I will organize the content of the flow into a separate blog~
redis [stream]: a detailed introduction to redis stream data types
Redis bit field (bitfield)
basic introduction
Purpose: In a word, a Redis string is regarded as an array composed of binary bits, and can address and modify variable-length bit-width and any specified integer bit field without byte alignment
The two functions are as follows:
- bit field modification
- overflow control
basic grammar
