Redis
This blog post was translated by Mistral
Open Redis official website, the first sentence states that Redis is an open-source, in-memory data structure store, commonly used for databases and caching. Redis is very common. Install Redis
You can install Redis from the official website. Just like SQLite, how do we use Redis in Python after installation?
pip install redis
``` Import redis module.\
>>> import redis\
Create a Redis object with given parameters.\
>>> r = redis.Redis(host='localhost', port=6379, db=0)\
Set key 'foo' to value 'bar'.\
>>> r.set('foo', 'bar')\
Return True if successful.\
True\
Get value of key 'foo'.\
>>> r.get('foo')\
Return value as bytes.\
b'bar' Python documentation provided some examples. Here comes something like `pip`. `pip` is a package manager. For what a package manager is, please refer to the "Getting Familiar with the Programming Environment" chapter. `pip` for `python` is similar to `Homebrew` for `macOS` system.
`pip` usually comes with the installation of `python`. If the computer has multiple versions of `Python` and `Pip`, the following two lines can be added to `~/.bash_profile`:
```shell
alias python=/usr/local/Cellar/python@3.9/3.9.1_6/bin/python3
alias pip=/usr/local/Cellar/python@3.9/3.9.1_6/bin/pip3
``` The meaning is to specify a certain version of `python` and `pip`. One way is to install it using `Homebrew`. Another way is to install it from the source code.
```bash
make
make test
make install
Translation:
Specify a certain version of Python and pip. One way is to install it using Homebrew. Another way is to install it from the source code.
Build process:
make make test make install Redis is starting Redis version 6.2.1 64 bit Warning: no config file specified, using the default config Increased maximum number of open files to 10032 (it was originally set to 4864) monotonic clock: POSIX clock_gettime … Server initialized 87684 M 10 Mar 2021 14:46:06.058 * Ready to accept connections
Version: 6.2.1 Open another terminal window for testing:
$ redis-cli 127.0.0.1:6379> set a 2 running the following code:
import redis
r = redis.Redis(host='localhost', port=6379, db=0)
result = r.get('a')
print(result)
The output of the code will be:
2
The Chinese text “127.0.0.1:6379> get a” translates to English as “running the following Redis command: get value for key ‘a’”. The number “2” is the value associated with key ‘a’ in the Redis database. r.set('foo', 'bar')
set value ‘bar’ for key ‘foo’ in Redis
print(r.get('foo'))
print the value associated with key ‘foo’ in Redis
Output:
shell
$ python fib_redis.py
b'bar'
I. Redis Cache Example for Fibonacci Sequence
To implement Fibonacci sequence using Redis. import redis
redis_instance = redis.Redis(host=’localhost’, port=6379, db=0)
def function(n): stored_number = redis_instance.get(n) if stored_number is not None: return int(stored_number) ``` if n < 2:
if statement condition is not met
res_n = n
else:
if statement condition is met
res_n = f(n-1) + f(n-2)
r.set(n, res_n)
set value of ‘r’ at index ‘n’ to ‘res_n’
return res_n
print(f(10))
Function definition and call
This function calculates the Fibonacci sequence recursively
def f(n): if n < 2: return n
else: return f(n-1) + f(n-2) This way it’s done.