The Gaps Between Clicks

A hard Data Modeling interview practice problem on DataDriven. Write and execute real data modeling code with instant grading.

Domain

Data Modeling

Difficulty

hard

Seniority

mid

Problem

We run a consumer web and mobile product that emits a high-volume clickstream: every page view, tap, and scroll lands as an event tied to a device, and a visitor is usually anonymous for a while before they sign in. Analysts need visit-level analysis (how long a session runs, how many events it holds, where it drops off) as well as daily engagement rolled up by page and device, where a session is activity with no more than a thirty-minute gap between consecutive events. Design a model that serves both the visit-level questions and the daily rollups, keeps a person's anonymous and signed-in activity connected, and still credits each visit to whoever was actually using the device at the time, since a shared device can later be handed to a different person.

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