A relational database like PostgreSQL: WAL and MVCC on one server, quorum replication and failover, then a sharded fleet.
Data engineers building storage, streaming and processing systems.
Your approach: Use diagrams or prose for data contracts, state ownership, throughput, ordering and recovery where the brief requires them.
Design a Relational Database like PostgreSQL. A relational database like PostgreSQL: WAL and MVCC on one server, quorum replication and failover, then a sharded fleet. Work from the scoping questions below. State assumptions for any unspecified load, guarantee or target, then trace your design end to end. Explain one difficult case and a credible alternative; the worked example is a reference, not a required implementation.
Resolve the scoping questions for a Relational Database like PostgreSQL. Separate stated behavior from assumptions, and identify what is outside your design.
Declare relevant volume, latency, freshness, quality or cost targets with units. Show calculations or an evaluation plan that can test them; unspecified targets are your assumptions, not hidden pass criteria.
Explain how your guarantees hold in a difficult case relevant to this subject. Address: Biggest table? Who else needs the changes?
Identify users, required behavior and exclusions. Answer: Scale? May a failover lose a commit?
Define the information owned by the system and the inputs, outputs and errors at its boundaries. Resolve: Availability? Read after write?
Estimate the dominant workload and resource demand with units and explicit assumptions. For a learned system, also state how quality is measured and what data is available.
Draw or describe the responsibilities needed for a Relational Database like PostgreSQL. Trace a representative request, event or job from its input to a visible result; identify durable state owners.
Walk through a difficult case step by step, including detection and recovery. Consider: Query shapes? Biggest table? Who else needs the changes?
Compare a credible alternative using your chosen workload and guarantees. Explain a remaining risk, a signal to watch and when you would change the design.