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How does caching improve system performance?

Q: How does caching improve system performance?

## Why caching helps A cache keeps **hot data in fast storage** (usually memory) close to the consumer. Reads hit the cache instead of the slow backing store, which **cuts latency** and **offloads the database**, so the same hardware serves far more traffic. The most common pattern is **cache-aside** (lazy loading): the app checks the cache first; on a miss it loads from the DB and populates the cache. App Cache in-memory</tex

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cache = {}                      # stand-in for Redis/Memcached

def load_from_db(key):
    print("  DB read for", key)
    return key.upper() + "-value"

def get(key):
    if key in cache:            # 1. check cache
        return cache[key]       # 2a. hit
    value = load_from_db(key)   # 2b. miss -> load
    cache[key] = value          # 3. populate
    return value

print(get("user:1"))            # miss -> DB
print(get("user:1"))            # hit  -> no DB read
print(get("user:2"))            # miss -> DB

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