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-- Before tuning: 2.4s
-- After  tuning:  18ms  (133× faster)

EXPLAIN (ANALYZE, BUFFERS)
SELECT  o.id, o.placed_at, c.email,
        sum(li.qty * li.unit_price) AS total
FROM    orders      o
JOIN    customers   c ON c.id = o.customer_id
JOIN    line_items  li ON li.order_id = o.id
WHERE   o.placed_at >= '2026-01-01'
GROUP BY o.id, c.email
HAVING  sum(li.qty * li.unit_price) > 500
ORDER BY total DESC
LIMIT   100;

-- Index Cond: line_items_order_id_idx
-- Planning Time: 0.42 ms
-- Execution Time: 17.8 ms