Code AnalysisHard 60s

Thundering herd with negative result

This endpoint is called for user-supplied IDs, some nonexistent. What is the failure?

Starter code

def get_profile(pid):
    p = cache.get(pid)
    if p is None:
        p = db.query("SELECT ... WHERE id=?", pid)  # returns None for bad ids
        if p is not None:
            cache.set(pid, p, 60)
    return p

system-design caching cache-penetration

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