Redis - common instructions

Redis - common instructions

1. Common commands for key

• del key1 key2 delete one or more key values
• rename key newkey Give the original key a new name
• move key 
• set key value Add a key and corresponding value value
• get key Get the corresponding value according to the key
• select index switches the warehouse number of the key storage. By default redis divides the memory for storing keys into 16 warehouses ranging from 0 to 15.
• keys s* (query all key values ​​starting with s) Fuzzy query keys stored in redis
• randomkey returns a random key
• exists key Enter a key and return whether the key exists
• type key View the type of a key value
• expire key 6 Set the key value to be valid for 6 seconds
• ttl key View the validity period of the key

2. String manipulation

• mset key value key value.... Set multiple key values ​​and corresponding value values
• mget key1 key2 Get the values ​​of multiple keys at the same time
• setrange key offset value Change the value corresponding to the key. (setrange str 3 s means that the value corresponding to str is shifted back to the fourth position and changed to s)
• append key value Append the value to the original value of the value
• The key value specified by incr key is incremented by 1, and the value after incrementing by 1 is returned.

Three, list linked list structure

• lpush key value inserts the value into the head of the value corresponding to the key
• rpush key value inserts the value at the end of the value corresponding to the key
• lrange key start stop Returns a range of values ​​in the linked list.

        

• lpop key pops up the leftmost value of the value value
• rpop key pops up the rightmost value of the value value
• LREM KEY_NAME COUNT VALUE delete n identical value values ​​corresponding to the key (lrem mylist 2 hi)
  
• LREM KEY_NAME COUNT VALUE (lrem mylist -1 hi) means that the index deletes 1 hi string from the right
  
• lindex key index (lindex mylist 2) query the corresponding value value according to the index value
• llen key calculates the length of this list

Four, set collection

1. A Redis Set is an unordered collection of type String. Collection members are unique, which means that duplicate data cannot appear in the collection.
2. Collections in Redis are implemented through hash tables, so the complexity of adding, deleting, and searching is O(1).
3. The maximum number of members in a collection is 232 - 1 (4294967295, each collection can store more than 4 billion members).

• sadd key member1 member2 add one or more members to the set
  
• smembers key returns all members in the collection
  
• srandmember key [count] Returns one or more random numbers in the collection
  
• scardkey gets the number of members of the set
  
• spop key removes a random element from the set
  
• sismemberkey member Determines whether an element is a member of the set key
  
• sinterkey1 [key2] returns the intersection of all sets given
  
• sunion key1 [key2] returns the union of all the given sets
  
• sdiff key1 [key2] returns the difference of all sets given
  

5. Ordered collection

• zadd key score member score member (zadd myset 1 hello 2 nihao) Add a member to the sorted set and set the member's serial number at the same time
• ZCARD KEY_NAME The Redis Zcard command is used to count the number of elements in a collection.
  
• ZCOUNT key min max The Redis Zcount command is used to count the number of members in the specified score interval in an ordered set.
  
• ZRANGE key start stop [ WITHSCORES ] Returns an ordered set with members in the specified range. ( The positions of the members are sorted by increasing fractional value (from small to large). )
  
• ZRANK key member If the member is a member of the sorted set key, return the rank of the member
  
• The ZREM key member is used to remove one or more members from the sorted set, non-existing members will be ignored.
  
• ZSCORE key member returns a sorted set, the member's score value.
  
• ZSCAN key cursor iterates over the elements in the sorted set (including element members and element scores)

Six, hash data structure

• HSET KEY_NAME FIELD VALUE (hset key name field field name value value name) hset book name The Legend of Condor Heroes hset book auth Jin Yong
  
• HGET KEY_NAME FIELD_NAME returns the value of the specified field in the hash table
  
• HGETALL KEY_NAME returns all fields and values ​​in the hash table
  
• HEXISTS KEY_NAME FIELD_NAME Check whether the specified field of the hash table exists
  
• HKEYS KEY_NAME get all field names in the hash table
  
• HLEN KEY_NAME get the number of fields in the hash table
• HMGET KEY_NAME FIELD1 ... FIELDN returns the value of one or more of the given fields in a hash table.
  
• HMSET KEY_NAME FIELD1 VALUE1 ... FIELDN VALUEN simultaneously sets multiple field-value pairs into a hash table
  
• HVALS KEY_NAME returns the values ​​of all fields in the hash table.
  

Seven, Redis global operation

• flushdb clears the contents of the current database, but does not clear the data of other databases.
• flushall flushes the contents of all databases.
• scan (Use the keys* command to list all keys. If there are many, it will generate a high value for memory IO, which will seriously lead to downtime. Therefore, the scan command is used to obtain the corresponding key in the form of a cursor instead of taking it out at one time.)
• scan 0 math k* Find the key starting with k, it will list the data that will not be, and give the position of the next offset.