How to Iterate Redis Keys with SCAN in Python

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 client to simulate SCAN iteration
    class MockRedis:
        def __init__(self):
            self.data = {f"user:{i}" for i in range(100)}
            self.data.update({f"post:{i}" for i in range(50)})
        
        def scan(self, cursor=0, match="*", count=10):
            keys = sorted(self.data)
            total = len(keys)
            start = cursor
            end = min(start + count, total)
            next_cursor = end if end < total else 0
            batch = [k for k in keys[start:end] if k.startswith(match.replace("*", ""))]
            return next_cursor, batch

    mock = MockRedis()
    user_keys = scan_keys(mock, pattern="user:*", count=20)
    post_keys = scan_keys(mock, pattern="post:*", count=20)
    print(f"Users: {len(user_keys)} keys")
    print(f"Posts: {len(post_keys)} keys")
    print(f"Total user keys sample: {sorted(user_keys)[:5]}")