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This article mainly explains "how to use Redis in Python". Interested friends may wish to have a look at it. The method introduced in this paper is simple, fast and practical. Let the editor take you to learn how to use Redis in Python.

Before we all use Redis client to use Redis, but in actual work, we mostly use Redis through code, because the editor is familiar with Python, so let's learn how to use Python to operate Redis today.

Environmental preparation

Redis needs to be installed first.

Python is installed (Python3 is recommended).

Redis's Python library is installed (pip install redis).

Begin to put it into practice.

Example: we plan to connect to Redis through Python. Then write a kv, and finally print out the v from the query.

Direct connection #! / usr/bin/python3import redis # Import redis module r = redis.Redis (host='localhost', port=6379, password= "pwd@321", decode_responses=True) # host is the redis host and password is the authentication password Redis default port is 6379r.set ('name',' phyger-from-python-redis') # key is "name" value is "phyger-from-python-redis" to store key-value pairs in redis cache print (r ['name']) # first: take out the value of key name print (r.get (' name')) # second: take out the value of name (type (r.get ('name')

Where get is the last command executed by the connection pool.

Connection pool

Usually, when you need to connect to the redis, a connection is created, based on which the redis operation is performed, and then released when the operation is completed. Under normal circumstances, this is no problem, but in the case of high concurrency, frequent connection creation and release will have a high impact on performance, so connection pooling plays a role.

The principle of connection pooling: multiple connections are created in advance, and when performing redis operations, the connections that have been created are directly obtained for operation. When complete, the connection is not released, but is returned to the connection pool for subsequent redis operations! This avoids continuous creation and release, thereby improving performance!

#! / usr/bin/python3import redis,time # Import the redis module. You can also operate the cache database directly on the server of the redis host via python. Pool = redis.ConnectionPool (host='localhost', port=6379, password= "pwd@321", decode_responses=True) # host is the redis host The default port of redis is 6379r = redis.Redis (connection_pool=pool) r.set ('name',' phyger-from-python-redis') print (r ['name']) print (r.get (' name')) # fetch the value print corresponding to the key name (type (r.get ('name'))

You will find that in practice, the effect of direct connection is the same as that of using connection pooling, except that there is a significant difference in high concurrency.

Basic exercise practice

For many Redis commands, we will take the SET command as an example.

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

The parameters of the set command in redis-py:

Parameter name definition ex expiration time (m) px expiration time (ms) nx if true, the current set operation executes xx only if name does not exist. If true, the current set operation executes ex only if name exists.

We plan to create a kv and set its ex to 3, expecting that the v of this k will become None in 3 seconds.

#! / usr/bin/python3import redis,time # Import the redis module. You can also operate the cache database directly on the server of the redis host via python. Pool = redis.ConnectionPool (host='localhost', port=6379, password= "pwd@321", decode_responses=True) # host is the redis host Redis default port is 6379r = redis.Redis (connection_pool=pool) r.set ('name',' phyger-from-python-redis',ex=3) print (r ['name']) # there should be vtime.sleep (3) print (r.get (' name')) # there should be no vprint (type (r.get ('name'))

Nx

Because the unit of px is too short, we will not do the demonstration, and the effect is the same as ex.

We plan to repeat the name that set has already set before, and if nothing happens, if nx is true, we will fail set. But if the name1 of set does not exist, it will succeed.

#! / usr/bin/python3import redis,time # Import the redis module. You can also operate the cache database directly on the server of the redis host via python. Pool = redis.ConnectionPool (host='localhost', port=6379, password= "pwd@321", decode_responses=True) # host is the redis host Redis default port is 6379r = redis.Redis (connection_pool=pool) r.set ('name',' phyger-0',nx=3) # set failed print (r ['name']) # should not be valid r.set (' name1', 'phyger-1',nx=3) # set success print (r.get (' name1')) # should be effective print (type (r.get ('name'))

As above, you will find that the set of name does not work because name already exists in the database. Name1's set is already in effect because name1 does not previously exist in the database.

Xx

We plan to repeat the name that set has already set before, and if nothing happens, when nx is true, we will set successfully. However, if the set does not exist in the name2, it will fail.

#! / usr/bin/python3import redis,time # Import the redis module. You can also operate the cache database directly on the server of the redis host via python. Pool = redis.ConnectionPool (host='localhost', port=6379, password= "pwd@321", decode_responses=True) # host is the redis host Redis default port is 6379r = redis.Redis (connection_pool=pool) r.set ('name',' phyger-0',xx=3) # set failure print (r ['name']) # should be changed to r.set (' name2', 'phyger-1',xx=3) # set success print (r.get (' name2')) # there should be no set success print (type (r.get ('name'))

At this point, I believe you have a deeper understanding of "how to use Redis in Python". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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