Materialized Views in Postgres: Trading Freshness for Speed

Every dashboard query that aggregates millions of rows on the fly is a ticking time bomb. It works fine with test data, gets slow with real data, and eventually someone adds a cron job that runs the same expensive query every five minutes "just to cache it." Postgres already has a primitive for this — materialized views — and most teams either don't know it exists or use it wrong.

The core tradeoff is simple: materialized views trade freshness for speed. The hard part isn't creating them; it's deciding how stale is acceptable and building a refresh strategy that doesn't lock your application while it runs.