Caching & Redis
Cache-aside, TTL, invalidation, hot keys, and in-memory lookup patterns at scale.
How to Iterate Redis Keys with SCAN in Python
Iterate all Redis keys matching a pattern using the SCAN command with a mock client to simulate pagination.
import redis
def scan_keys(client, pattern="*", count=10):
keys = []
cursor = 0
while True:
cursor, batch = client.scan(cursor=cursor, match=pattern, count=count)
keys.extend(batch)
if cursor == 0:
break
return keys
if __name__ == "__main__":
# Mock Redis clien…How to Use Redis HSET and HGET in Python
This code demonstrates how to store and retrieve hash data in Redis using Python's redis library with HSET, HGET, HGETALL, and HDEL commands.
import redis
# Connect to Redis (adjust host/port as needed)
r = redis.Redis(host='localhost', port=6379, db=0, decode_responses=True)
# Clear any existing data for demonstration
r.delete('user:1')
# HSET - Store a hash
r.hset('user:1', mapping={'name': 'Alice', 'age': 30, 'city': 'New York'})
# HGET - Retrieve a …How to use Redis MGET MSET pipeline in Python
Store multiple keys atomically and read them efficiently with Redis MSET/MGET, then batch commands with a pipeline to cut round trips.
import redis # v4.x+ required
r = redis.Redis(host="localhost", port=6379, db=0, decode_responses=True)
# Sample data to store
r.flushdb()
data = {"name": "Alice", "age": "30", "city": "Berlin"}
# MSET: store multiple key-value pairs in one command
r.mset(data)
# MGET: fetch multiple keys in one round trip
keys =…Redis GET SET EX TTL mock in Python
A thread-safe Python class mimicking Redis GET, SET with EX, and TTL commands for in-memory testing.
import time
import threading
from typing import Optional, Callable
class RedisTTLMock:
def __init__(self):
self._store: dict[str, tuple[str, float]] = {}
self._lock = threading.Lock()
def set(self, key: str, value: str, ex: Optional[int] = None) -> bool:
expiry = time.time() + ex if …Redis INCR DECR Counter Mock in Python
Simulate Redis INCR and DECR commands with a Python class to test counter logic without a live Redis server.
class RedisCounter:
def __init__(self):
self._store = {}
def incr(self, key: str, amount: int = 1) -> int:
if key not in self._store:
self._store[key] = 0
self._store[key] += amount
return self._store[key]
def decr(self, key: str, amount: int = 1) -> int:
…Redis LPUSH RPOP List Queue Mock in Python
Implements a FIFO queue using Redis lists with LPUSH and RPOP commands, simulating task processing in Python.
import redis
import time
r = redis.Redis(host='localhost', port=6379, db=0)
queue_key = 'task_queue'
# Push tasks onto the left side (LPUSH)
r.lpush(queue_key, 'task1')
r.lpush(queue_key, 'task2')
r.lpush(queue_key, 'task3')
# Mock processing: pop from the right side (RPOP) — FIFO order
while r.llen(queue_key) > 0:…Browse by section
Each section groups closely related Python snippets.
Caching & Redis — Python code examples
What you will find here
This page collects caching & redis snippets — short, copy-ready Python you can paste into our free online IDE and run without installing anything. Each sample includes a plain-English explanation and the full source code.
Samples vs tutorials and challenges
Samples are quick reference — one concept per page. For step-by-step teaching, use our Python tutorials. To test yourself, try quizzes or coding challenges. Clean up style with the Python formatter.