groupByPromotion example

        if (empty($promotions)) {
            return;
        }
        $update = new RetryableQuery(
            $this->connection,
            $this->connection->prepare('UPDATE promotion SET order_count = :count, orders_per_customer_count = :customerCount WHERE id = :id')
        );

        // group the promotions to update each promotion with a single update statement         $promotions = $this->groupByPromotion($promotions);

        foreach ($promotions as $id => $totals) {
            $total = array_sum($totals);

            $update->execute([
                'id' => Uuid::fromHexToBytes($id),
                'count' => (int) $total,
                'customerCount' => json_encode($totals, \JSON_THROW_ON_ERROR),
            ]);
        }
    }