Procedimientos almacenados y parámetros de consulta en ClickHouse

DELIMITER $$

CREATE PROCEDURE process_order(
    IN p_order_id INT,
    IN p_customer_id INT,
    IN p_order_total DECIMAL(10,2),
    OUT p_status VARCHAR(50),
    OUT p_loyalty_points INT
)
BEGIN
    DECLARE v_customer_tier VARCHAR(20);
    DECLARE v_previous_orders INT;
    DECLARE v_discount DECIMAL(10,2);

    -- Iniciar transacción
    START TRANSACTION;

    -- Obtener información del cliente
    SELECT tier, total_orders
    INTO v_customer_tier, v_previous_orders
    FROM customers
    WHERE customer_id = p_customer_id;

    -- Calcular descuento según el nivel
    IF v_customer_tier = 'gold' THEN
        SET v_discount = p_order_total * 0.15;
    ELSEIF v_customer_tier = 'silver' THEN
        SET v_discount = p_order_total * 0.10;
    ELSE
        SET v_discount = 0;
    END IF;

    -- Insertar registro de pedido
    INSERT INTO orders (order_id, customer_id, order_total, discount, final_amount)
    VALUES (p_order_id, p_customer_id, p_order_total, v_discount,
            p_order_total - v_discount);

    -- Actualizar estadísticas del cliente
    UPDATE customers
    SET total_orders = total_orders + 1,
        lifetime_value = lifetime_value + (p_order_total - v_discount),
        last_order_date = NOW()
    WHERE customer_id = p_customer_id;

    -- Calcular puntos de fidelidad (1 punto por dólar)
    SET p_loyalty_points = FLOOR(p_order_total - v_discount);

    -- Insertar transacción de puntos de fidelidad
    INSERT INTO loyalty_points (customer_id, points, transaction_date, description)
    VALUES (p_customer_id, p_loyalty_points, NOW(),
            CONCAT('Order #', p_order_id));

    -- Comprobar si el cliente debe subir de nivel
    IF v_previous_orders + 1 >= 10 AND v_customer_tier = 'bronze' THEN
        UPDATE customers SET tier = 'silver' WHERE customer_id = p_customer_id;
        SET p_status = 'ORDER_COMPLETE_TIER_UPGRADED_SILVER';
    ELSEIF v_previous_orders + 1 >= 50 AND v_customer_tier = 'silver' THEN
        UPDATE customers SET tier = 'gold' WHERE customer_id = p_customer_id;
        SET p_status = 'ORDER_COMPLETE_TIER_UPGRADED_GOLD';
    ELSE
        SET p_status = 'ORDER_COMPLETE';
    END IF;

    COMMIT;
END$$

DELIMITER ;

-- Llamar al procedimiento almacenado
CALL process_order(12345, 5678, 250.00, @status, @points);
SELECT @status, @points;

# Ejemplo en Python usando clickhouse-connect
import clickhouse_connect
from datetime import datetime
from decimal import Decimal

client = clickhouse_connect.get_client(host='localhost')

def process_order(order_id: int, customer_id: int, order_total: Decimal) -> tuple[str, int]:
    """
    Processes an order with business logic that would be in a stored procedure.
    Returns: (status_message, loyalty_points)

    Note: ClickHouse is optimized for analytics, not OLTP transactions.
    For transactional workloads, use an OLTP database (PostgreSQL, MySQL)
    and sync analytics data to ClickHouse for reporting.
    """

    # Paso 1: Obtener información del cliente
    result = client.query(
        """
        SELECT tier, total_orders
        FROM customers
        WHERE customer_id = {cid: UInt32}
        """,
        parameters={'cid': customer_id}
    )

    if not result.result_rows:
        raise ValueError(f"Customer {customer_id} not found")

    customer_tier, previous_orders = result.result_rows[0]

    # Paso 2: Calcular el descuento según el nivel (lógica de negocio en Python)
    discount_rates = {'gold': 0.15, 'silver': 0.10, 'bronze': 0.0}
    discount = order_total * Decimal(str(discount_rates.get(customer_tier, 0.0)))
    final_amount = order_total - discount

    # Paso 3: Insertar el registro del pedido
    client.command(
        """
        INSERT INTO orders (order_id, customer_id, order_total, discount,
                           final_amount, order_date)
        VALUES ({oid: UInt32}, {cid: UInt32}, {total: Decimal64(2)},
                {disc: Decimal64(2)}, {final: Decimal64(2)}, now())
        """,
        parameters={
            'oid': order_id,
            'cid': customer_id,
            'total': float(order_total),
            'disc': float(discount),
            'final': float(final_amount)
        }
    )

    # Paso 4: Calcular las nuevas estadísticas del cliente
    new_order_count = previous_orders + 1

    # En bases de datos analíticas, se prefiere INSERT sobre UPDATE
    # Esto utiliza un patrón ReplacingMergeTree
    client.command(
        """
        INSERT INTO customers (customer_id, tier, total_orders, last_order_date,
                              update_time)
        SELECT
            customer_id,
            tier,
            {new_count: UInt32} AS total_orders,
            now() AS last_order_date,
            now() AS update_time
        FROM customers
        WHERE customer_id = {cid: UInt32}
        """,
        parameters={'cid': customer_id, 'new_count': new_order_count}
    )

    # Paso 5: Calcular y registrar los puntos de fidelidad
    loyalty_points = int(final_amount)

    client.command(
        """
        INSERT INTO loyalty_points (customer_id, points, transaction_date, description)
        VALUES ({cid: UInt32}, {pts: Int32}, now(),
                {desc: String})
        """,
        parameters={
            'cid': customer_id,
            'pts': loyalty_points,
            'desc': f'Order #{order_id}'
        }
    )

    # Paso 6: Verificar si hay ascenso de nivel (lógica de negocio en Python)
    status = 'ORDER_COMPLETE'

    if new_order_count >= 10 and customer_tier == 'bronze':
        # Ascender a silver
        client.command(
            """
            INSERT INTO customers (customer_id, tier, total_orders, last_order_date,
                                  update_time)
            SELECT
                customer_id, 'silver' AS tier, total_orders, last_order_date,
                now() AS update_time
            FROM customers
            WHERE customer_id = {cid: UInt32}
            """,
            parameters={'cid': customer_id}
        )
        status = 'ORDER_COMPLETE_TIER_UPGRADED_SILVER'

    elif new_order_count >= 50 and customer_tier == 'silver':
        # Ascender a gold
        client.command(
            """
            INSERT INTO customers (customer_id, tier, total_orders, last_order_date,
                                  update_time)
            SELECT
                customer_id, 'gold' AS tier, total_orders, last_order_date,
                now() AS update_time
            FROM customers
            WHERE customer_id = {cid: UInt32}
            """,
            parameters={'cid': customer_id}
        )
        status = 'ORDER_COMPLETE_TIER_UPGRADED_GOLD'

    return status, loyalty_points

# Usar la función
status, points = process_order(
    order_id=12345,
    customer_id=5678,
    order_total=Decimal('250.00')
)

print(f"Status: {status}, Loyalty Points: {points}")

SET param_name = 'John Doe';
SET param_age = 25;
SET param_salary = 75000.50;

SELECT name, age, salary FROM users
WHERE name = {name: String}
  AND age >= {age: UInt8}
  AND salary <= {salary: Float64};

SET param_date = '2024-01-15';
SET param_timestamp = '2024-01-15 14:30:00';

SELECT * FROM events
WHERE event_date = {date: Date}
   OR event_timestamp > {timestamp: DateTime};

SET param_ids = [1, 2, 3, 4, 5];

SELECT * FROM products WHERE id IN {ids: Array(UInt32)};

SET param_filters = {'target_status': 'active'};

SELECT user_id, status, type FROM accounts
WHERE status = arrayElement(
    mapValues({filters: Map(String, String)}),
    indexOf(mapKeys({filters: Map(String, String)}), 'target_status')
);

SET param_table = 'sales_2024';

SELECT count() FROM {table: Identifier};