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While this loads — worth knowing
ElastiCache RedisnotElastiCache Memcached
Redis has data structures — sorted sets, counters, pub/sub. Memcached has plain keys and nothing else.
Loading…
While this loads — worth knowing
Redis has data structures — sorted sets, counters, pub/sub. Memcached has plain keys and nothing else.
Architecture pattern
when uploads need heavy work that nobody is waiting on
Upload and processing are separate problems. The upload lands in S3 and returns immediately; the event queues the work; workers scale on queue depth and take minutes if they need to. A failed job retries without blocking the next one, and the finished asset is served from the edge.
In the order a request or a record moves through it. Each one links to the page that explains it.
Phrases that, when you meet them in a scenario, mean this shape rather than another. They are the tell, and they are what an exam question is built around.
The user needs somewhere to see progress, because "done" now arrives long after "uploaded".
Every shape has one. A design decision with no stated downside is usually a decision nobody has finished making.
These run through some of the same services, which is exactly why a brief that fits one can look like it fits another.
Reading a shape and producing one from a scenario that never names a service are different skills, and the exam asks for the second. The scenarios give you the brief; you draw the architecture and it is scored against what the brief requires.