Super detailed tutorial of Python operating redis database

Introduce

Common data structure

install

Connect

String character string （ Key value pair ）

List list

Hash Hash

Set aggregate

Zset Ordered set

Bitmap Bitmap

Global function

summary

Redis Is an open source, memory based and persistent Key-Value database , use ANSI C Language writing . It has a rich data structure , Have transaction function , Ensure the atomicity of the command . Because it's an in memory database , Reading and writing is very fast , Can be up to 10w/s Evaluation rate of , Therefore, it is generally applied to data that changes rapidly 、 Real time communication 、 Cache, etc . But memory database usually needs to consider the memory size of the machine .

Redis Yes 16 A logical database （db0-db15）, Each logical database project is isolated , By default db0 database . If you choose the second 2 A database , Through the command select 2 ,python You can specify the database when connecting to .

String- character string

List- list

Hash- Hash

Set- aggregate

ZSet- Ordered set

Bitmap- Bitmap

python We use redis-py Library to operate Redis database , The following will focus on .

Premise ： To be installed Redis database , If there is no installation point here

The first way ： Ordinary

The second way ： Connection pool

redis The return value types of Chinese characters are bytes （bytes） type

stay redis in , A key corresponds to a value

1.String set Set a single key value

set(name, value, ex=None, px=None, nx=False, xx=False)

ex： Expiration time （ second ）, When it's time redis It will be deleted automatically

px： Expiration time （ millisecond ）, When it's time redis It will be deleted automatically .ex、px One out of two

nx： If set to True, only name When there is no , At present set Operation before execution

xx： If set to True, only name In existence , At present set Operation before execution

2.String get Get a single value

3.String mset Set multiple key values

mset(*args, **kwargs)

perhaps

4.String mget Get multiple values

mget(keys, *args)

5.String getset Set new values for existing keys , And return the original value

getset(name, value)

When the given key does not exist , Will set its new value , But the return value is None

6.String setrange Modify a key according to the index value value

setrange(name, offset, value)

The return value is ： Modified string length

name： key , Automatically add when the given does not exist

offset： Offset , With 0 Start

value： Modified character or string , String with offset Go backwards

7.String getrange Get the part of a key according to the index value value

If the given key does not exist , Returns a null value b''

getrange(key, start, end)

The result is ：

8.String strlen obtain value The length of

strlen(name)

When the given key does not exist , The return value is 0

9.String incr int Type of value Self increasing （ Self reduction ）

Empathy ： Self reduction ,decr(name, amount=1)

The value corresponding to the given key must be an integer or string value , Otherwise, it will report a mistake . The default auto increment is 1

incr(name, amount=1)

The return value is ： Modified value ,int type

10.String incrbyfloat Floating point number type value Self increasing

incrbyfloat(name, amount=1.0)

The return value is ： Floating point type float

11.String append value Back up

append(key, value)

If given key does not exist , Then set a new value

The return value is the length of the modified string

The result is ：

stay redis in , A key corresponds to a list

12.List lpush Add values to the left of the list rpush（ On the right ）

lpush(name, *values)

value When there are multiple values , Add... To the left of the list from left to right , The types can be different

When the given key does not exist , Create a new list

Return value ： The size of the list

13.List lpushx When the bond exists , Add to the left of the list rpushx（ Far right ）

lpushx(name, value)

When only keys exist , Just add . If the key does not exist, do not add , Or create a new list

The return value is ： List size

14.List llen Get the list size of the given key

llen(name)

15.List linsert Insert a new value in the middle of the list

linsert(name, where, refvalue, value)

name： Key name

where： Location , front （BEFORE） Or behind （AFTER）

refvalue： Specify which value to insert before and after

value： Insert new value

Return value ： The length of the list after insertion , If returns -1, be refvalue non-existent

Data before insertion ：

The inserted data ：

16.List lset The list is assigned by index

lset(name, index, value)

Return value ： success True otherwise False

17.List lindex Get list values by index

lindex(name, index)

18.List lrange Get a piece of data from the list

lrange(name, start, end)

Return value ：List A piece of data of type

19.List lpop Delete the first value on the left rpop（ On the right ）

lpop(name)

Return value ： The value of the deleted element

20.List lrem Delete... From the list N Two identical values

lrem(name, value, num=0)

name： Key name

value： Values to be deleted

num： Number of deletions An integer indicates left to right Negative numbers indicate right to left for example ：2 -2

Return value ： Return the number of deletions

21.List ltrim Delete all values outside the range in the list

ltrim(name, start, end)

Return value ： success True

22.List blpop Delete and return the leftmost value in the list brpop（ Far right ）

blpop(keys, timeout=0)

keys： Given key

timeout： Waiting timeout , The default is 0, To wait for

Return value ：tuple type Form like ： ( Key name , Deleted values ) (b'Zarten', b'hehe')

23.List rpoplpush The rightmost value in one list is taken out and added to the leftmost value in another list brpoplpush Blocking version

rpoplpush(src, dst)

brpoplpush(src, dst, timeout=0) by rpoplpush Blocking version of ,timeout by 0 when , Always block

Return value ： Extracted element value

It is internally stored as key value pairs

24.Hash hset Add a key value pair to the hash

hset(name, key, value)

key There is , The modified , Otherwise, add

Return value ： Return the number of successful additions int

25.Hash hmset Set multiple key value pairs in the hash

hmset(name, mapping)

mapping：dict type

Return value ： success True

26.Hash hmget Get multiple key value pairs in the hash

hmget(name, keys, *args)

Return value ： List of values list Form like ： [b'1', b'123'] <class 'list'>

27.Hash hget Get specified key Value

hget(name, key)

28.Hash hgetall Get all key value pairs in the hash

hgetall(name)

Return value ：dict type

29.Hash hlen Get the number of key value pairs in the hash

hlen(name)

30.Hash hkeys Get all the keys in the hash key

hkeys(name)

Return value ：list type

31.Hash hvals Get all the values in the hash value

hvals(name)

Return value ：list type

32.Hash hexists Check if there is a key in the hash key

hexists(name, key)

Return value ： Yes True ; otherwise False

33.Hash hdel Delete key value pairs in hash （key-value）

hdel(self, name, *keys)

Return value ：int Number of deletions

34.Hash hincrby Auto incrementing hash key Corresponding value value （ Must be integer numeric type ）

hincrby(name, key, amount=1)

If given key Create if it does not exist ,amount Default increase 1, Can be negative

Return value ：int Increased value

35.Hash hincrbyfloat Self-incremented floating point number ditto hincrby

hincrbyfloat(name, key, amount=1.0)

36.Hash expire Set the expiration time of the entire key

expire(name, time)

time： second , Time is up. , Automatically delete immediately

37.Hash hscan Incrementally iterate to get the data in the hash

hscan(name, cursor=0, match=None, count=None)

name：redis Of name

cursor： The cursor （ Fetch data in batches based on cursors ）

match： Matching the specified key, Default None Represents all key

count： Minimum number of slices per slice , Default None Said the Redis The default number of slices

Return value ：tuple type ;（ Scanning position , all dict data ）

38.Hash hscan_iter return hscan The generator

hscan_iter(name, match=None, count=None)

Refer to the above function hscan

The elements in the set do not repeat , Generally used to filter elements

39.Set sadd Add elements to the collection

sadd(name, *values)

If you insert an existing element , Will not be inserted automatically

40.Set scard Returns the number of elements in the collection

scard(name)

41.Set smembers Get all the elements in the collection

smembers(name)

Return value ：set type , Form like ： {b'a', b'apple', b'c', b'b'}

42.Set srandmember Get one or at random N Elements

srandmember(name, number=None)

name： Key name

number： One or more N individual , The default is to return a . If returns N individual , Then return to List type

Return value ： Return a value or a list

43.Set sismember Determine whether a value is in the set

sismember(name, value)

Return value ：True stay False be not in

44.Set spop Randomly delete and return the elements in the collection

spop(name)

45.Set srem Delete one or more elements in the collection

srem(name, *values)

Return value ： Return the number of deletions int

46.Set smove Move values from one set to another

smove(src, dst, value)

if value When there is no , return False

Return value ： success True

47.Set sdiff Returns all elements in one collection but not in other collections （ Difference set ）

sdiff(keys, *args)

stay keys Collection , Elements that are not in other collections

Return value ：set type {b'2', b'4', b'3', b'1'}

48.Set sdiffstore above sdiff The return value of （ Difference set ） Save in another collection

sdiffstore(dest, keys, *args)

stay keys Collection , Elements that are not in other collections are saved in dest Collection

dest： New collection , New set of settings , The old collection will be overwritten

Return value ：int Returns the number of actions

49.Set sinter Returns the intersection of a set and other sets

sinter(keys, *args)

Return value ：set type

50.Set sinterstore Returns the intersection of a set and other sets , And save it in another set

sinterstore(dest, keys, *args)

dest： Another collection , Set up a new set , The old collection elements will be overwritten

51.Set sunion Returns the union of a set and other sets

sunion(keys, *args)

52.Set sunionstore Returns the union of a set and other sets , And save it in another set

sunionstore(dest, keys, *args)

dest： Another collection , Set up a new set , The old collection elements will be overwritten

Return value ： Number of new collection elements

An ordered set has one more fractional field than a set , Fractions can be sorted in ascending and descending order

53.Zset zadd Add elements to an ordered set

zadd(name, *args, **kwargs)

When adding an element, you need to specify the score of the element

Return value ： Returns the number of additions

2 The ways are as follows ：

54.Zset zcard Returns the number of elements in an ordered collection

zcard(name)

55.Zset zcount Returns the number of elements within the fractional range in an ordered set

zcount(name, min, max)

contain min max

Return value ： Number int

56.Zset zscore Returns the fraction of a specified value in an ordered set

zscore(name, value)

Return value ：float Score of type ; Form like ： -5.0 <class 'float'>

57.Zset zincrby Increase the score of a value in an ordered set

zincrby(name, value, amount=1)

value： If exist , Increase its amount fraction ; If it does not exist , Then add the new value and the corresponding score

amount： Increased value , Can be negative

Return value ： Increased score float type ; Form like ： -5.0 <class 'float'>

58.Zset zrem Delete one or more values in an ordered set

zrem(name, *values)

Return value ： Return the number of deletions

59.Zset zremrangebyrank Delete the ordered collection elements according to the sorting range

zremrangebyrank(name, min, max)

Return value ： Delete the number int

Delete it as shown in the figure below ：

60.Zset zremrangebyscore Delete ordered set according to score range

zremrangebyscore(name, min, max)

Return value ： Delete the number int

61.Zset zrank Returns the rank of a value in an ordered set （ From small to large ） zrevrank（ From big to small ）

zrank(name, value)

Return value ：value stay name Score ranking value in , Rank the scores from small to large , from 0 Start

The return value is shown in the following figure ：

62.Zset zrange Returns a piece of data sorted by the scores of an ordered set

zrange(name, start, end, desc=False, withscores=False, score_cast_func=float)

name：redis Of name

start： An ordered collection index starting position （ The score ）

end： End of index of ordered collection （ The score ）

desc： Sort rule , By default, sort by score from small to large

withscores： Whether to get the score of the element , The default is to get only the values of the elements

score_cast_func： A function that converts data to scores

Return value ：list type [(b'tt', 10.0), (b'd', 6.0), (b'c', 5.0)] <class 'list'>

The result is shown in Fig. ：

bitmap Bit in which binary is stored 0 and 1, Similar to digit group . Typical applications are based on redis The bloom filter .

Belong to String String data structure , solid bit The mapping is limited to 512 MB within （2^32）

63.Bitmap setbit Set the value of the bitmap

setbit(name, offset, value)

name：redis Key name

offset： Offset , Greater than or equal to 0. When offset stretches , Blank space to 0 fill

value： Binary value 0 or 1

64.Bitmap getbit Returns the value of the specified offset of the bitmap

getbit(name, offset)

return 0 or 1

65.Bitmap bitcount The binary in the returned bitmap is 1 Total number of

bitcount(key, start=None, end=None)

start end Specify the start and end bits , Default entire bitmap

Global functions apply to any data structure

66. Global function delete Delete redis All data for one or more keys in

delete(*names)

Return value ：int Number of deletions

67. Global function exists Judge redis Is there a key in

exists(name)

Return value ： There is True; conversely False

68. Global function rename rename redis Middle key name

rename(src, dst)

Return value ： success True

69. Global function move Move redis All data of a key in a key to a key db in

move(name, db)

Return value ： success True

70. Global function randomkey Random access redis A key name in

randomkey()

Return value ： Form like ： b'name_55'

71. Global function type see redis A key data structure type in

type(name)

Return value ： character string （ Byte form ） Form like ： b'hash'

none (key non-existent )

string ( character string )

list ( list )

set ( aggregate )

zset ( Ordered set )

hash ( Hashtable )

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