InterviewsVector
ExpertDistinguishedPerformance, Observability & Capacity75 minutesPro answer

SDV-054

Detect silent data loss in a multi-stage pipeline before customers do

Design end-to-end completeness signals, invariants, lineage, quarantine, and repair when every component reports healthy while records disappear.

ObservabilityReconciliationEvent DrivenAuditability

Interview prompt

Problem context

A revenue-reporting pipeline spans CDC, queues, transforms, object storage, and warehouse loads. All services show green uptime, but a tenant notices transactions missing from reports. Retries and duplicates are expected; schemas and partitions evolve. Design correctness observability and repair.

Skills being evaluated

data correctnessend-to-end observabilityreconciliationownership design

The full reasoning guide is part of Pro

The scenario and evaluation focus above remain public. Pro unlocks the structured answer, trade-off analysis, follow-up probes, common weak answers, rubric, related reasoning, and any architecture diagram.

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What the full guide covers

Clarify the decision
Establish scale assumptions
Functional and non-functional requirements
High-level architecture
Data model and flow
Consistency and transaction boundaries
Failure modes and recovery
Security and privacy
Observability and SLOs
Capacity and cost
Alternatives and trade-offs
Evolution and migration
What Staff and Principal candidates should emphasize

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Choose metrics, traces, logs, exemplars, retention, and tenant debugging paths without letting unbounded labels bankrupt or disable telemetry.

Staff · 55 min

Reconcile years of dual writes after partial failures were normalized

Recover truth when two stores have silently diverged, with explicit authority rules, bounded repair, customer impact controls, and recurrence prevention.

Senior · 50 min

Define SLOs and error-budget policy for a product with unequal journeys

Choose customer-centered indicators, windows, targets, and policy actions without averaging away critical tenants or turning SLOs into vanity dashboards.