The analytics team wants a single event history across the website and mobile app.
The web_events and mobile_events tables each record a user_id and an event timestamp (event_ts). Combine the events from both sources into one chronological report.
Every event record must be included, even when two records have the same user and timestamp. The combined report should not decide whether identical records represent duplicates in the underlying event stream.
Ordering: Sort by event_ts in ascending order.