Materialized Views — předpočítané pohledy

Materialized views pro výkon čtení. PostgreSQL a event-driven aktualizace.

PostgreSQL

CREATE MATERIALIZED VIEW order_summary AS
SELECT c.id, c.name, COUNT(o.id) as orders, SUM(o.total) as total
FROM customers c LEFT JOIN orders o ON c.id = o.customer_id
GROUP BY c.id, c.name;

CREATE UNIQUE INDEX idx_os_cust ON order_summary(id);
REFRESH MATERIALIZED VIEW CONCURRENTLY order_summary;

Event-Driven

eventBus.on('OrderCreated', async (e) => {
    await db.query(\`
        INSERT INTO order_summary (customer_id, orders, total)
        VALUES ($1, 1, $2)
        ON CONFLICT (customer_id) DO UPDATE SET
            orders = order_summary.orders + 1,
            total = order_summary.total + $2
    \`, [e.customerId, e.total]);
});

Shrnutí

Materialized views = zásadní optimalizace čtení. Zvažte freshness vs performance trade-off.