Backend & systems·Data modelling and storage engines
you precompute the expensive aggregate into a real table and refresh it on a schedule instead of recomputing it per request.
Materialised view
A stored, physically persisted result of a query, refreshed either on demand or incrementally. It converts a slow read into a fast one and moves the cost to refresh time. Refresh is the whole design problem: a full refresh locks or duplicates the data, and an incremental one needs you to know exactly which inputs changed.