Projection

ELI5 — The Vibe Check

A projection transforms raw events into a useful read model. Every time an 'OrderPlaced' event fires, the projection updates the dashboard table. It's like a live scoreboard operator who watches the game events and keeps the scoreboard updated.

Real Talk

In event sourcing, a projection is a function that processes a stream of events to build or update a read model/view. Projections can be synchronous (inline) or asynchronous, can be replayed from the beginning of the event stream, and multiple projections can produce different views from the same events.

When You'll Hear This

"We have three projections from the same event stream — one for the dashboard, one for analytics, one for search." / "If the projection is wrong, just fix it and replay all the events to rebuild the view."