REPEAT CUSTOMER QUERY - PostgreSQL

SELECT
  c.customer_id,
  c.name,
  q3.amount as q3_total,
  q4.amount as q4_total,
  ROUND((q4.amount - q3.amount) / q3.amount * 100, 1) as growth_pct
FROM customers c
LEFT JOIN (
  SELECT customer_id, SUM(amount) as amount
  FROM orders
  WHERE date_trunc('quarter', order_date) = '2026-Q3'
  GROUP BY customer_id
) q3 ON c.customer_id = q3.customer_id
LEFT JOIN (
  SELECT customer_id, SUM(amount) as amount
  FROM orders
  WHERE date_trunc('quarter', order_date) = '2026-Q4'
  GROUP BY customer_id
) q4 ON c.customer_id = q4.customer_id
WHERE
  q3.amount IS NOT NULL
  AND q4.amount IS NOT NULL
  AND q4.amount > q3.amount
ORDER BY growth_pct DESC;

EXECUTION PLAN

Seq scan on orders q4: 12ms
Hash join on customer_id: 8ms
Sort by growth_pct: 4ms
Total: 24ms

OPTIMIZATION

Index on orders(customer_id, order_date) cuts query to 6ms
Add if run frequency > 2x daily

ORM EQUIVALENT (Prisma)

const repeatCustomers = await prisma.$queryRaw`
  ...same query above
`;