It seems like good practice is to check data retrieved from the cache is what is expected, e.g. the user id from the cache matches the logged-in user id.
Unfortunately, most devs don't think there is ever a need to check that until it fails.
Unfortunately, most devs don't think there is ever a need to check that until it fails.
Something like: user_profile_bio.[user_id]
If that returns the wrong bio from Redis, then something is broken in Redis, no? Or are you suggesting that I create some sort of format that duplicates the user id in the data itself?
Undoubtedly you are sure this won't ever go wrong, but all it takes is someone else to cache something at user_profile_bio.[customer_id] and you've got a problem (at best it won't work, at worst you'll get the wrong user profile).
Imagine instead of a user profile at Royal Mail this was patient data in a hospital. Getting this information wrong could endanger someone's life.
And mistakes with private data that isn't safety critical can still cost a hefty fine from a government data protection office, or bad publicity and damage to your reputation.
If you're doing:
SELECT * FROM serious_money_table WHERE user_id = :user_id;
The thing is that a function like
def get_profile(user_id):
profile = fetch_profile(user_id)
assert profile.user_id == user_id
return user_id