Interview Q&A / System Design
System Design interview questions
Caching, scaling, databases and classic design problems for beginners.
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- What is the PACELC theorem and how does it extend CAP?
PACELC says: if there is a Partition, choose Availability or Consistency; Else, when running normally, choose between Latency and Consistency. It captures that consistency costs latency even when nothing is broken.
AdvancedQuick answer1 min read - What is the transactional outbox pattern and what problem does it solve?
It solves the dual-write problem: updating a database and publishing an event can't be atomic. The outbox writes the event into a table in the same database transaction, and a separate process publishes it to the broker.
AdvancedQuick answer1 min read