20 · Domain — MOC

Up: plan

Event streams, clickstream, web analytics — the subject-matter substrate. This is where an engineering background is an asset.

Subject knowledge

• What is a clickstream — events, sessions, users, identity stitching
• Sessionization — windowing strategies, timeout choices, the boundary problem
• Event schema and drift — schema evolution, new event types, reprocessing
• Funnels and journeys — conversion paths, drop-off, multi-touch
• Attribution models — last-touch, position-based, data-driven; their failure modes
• Concept drift in production — seasonality, campaigns, bot waves; detection & retraining
• Online vs offline gap — why offline lift so often dies in the A/B test ⚠️ (a core trap)
• Bots, fraud, and invalid traffic — the anomaly side of the domain
• Privacy & consent constraints — GDPR, cookieless, what data I can actually use

Query & compute substrate

• DuckDB for local event analytics — Parquet, sessionize, funnels on a laptop
• ClickHouse — when local stops scaling (built for this exact workload)
• Polars over pandas — event tables get big
• Batch vs streaming decision — Kafka/Flink only if in-flight latency genuinely matters

→ The full local toolchain (install + why each tool) is documented in Offline compute stack.