Systems 101
A tiny sampler that checks a few basics — pick an answer and see what happens.
Welcome
This short course asks you three questions. Pick an answer, read why, and move on.
quiz
Which best describes a server?
A server is a process that waits for requests from clients and sends back responses.
quiz
What is a database mainly for?
A database persists data so it survives restarts and can be queried efficiently.
quiz
What problem does a cache mainly solve?
A cache stores frequently-read results so requests avoid hitting the slower database every time.
run · sql
Write SQL that returns the NAMES of the users who are admins (any order).
Hint: Filter the users table by role = 'admin'.
decide · arch
Black Friday is coming — how do you add headroom?
Live architecture — watch the requests flow, then pick a strategy to see what changes.
Live architecture — watch the requests flow, then pick a strategy to see what changes.
The DB connection pool is the binding limit here. Raising it multiplies headroom for free; scaling the API tier in front of it costs ~32% more and buys nothing.
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