microwind/ai-skills/read-model-optimization

-- 写模型：规范化（多表）
-- orders, order_items, customers, products（4张表，需要JOIN）
 
-- 读模型：反规范化（一张视图）
CREATE TABLE order_summary_view (
    order_id VARCHAR PRIMARY KEY,
    customer_name VARCHAR,
    customer_email VARCHAR,
    total_amount DECIMAL,
    item_count INT,
    status VARCHAR,
    created_at TIMESTAMP
);
-- 查询时零 JOIN，直接读取

// 监听事件更新读模型
@EventHandler
public class OrderReadModelProjector {
    private final JdbcTemplate jdbc;
 
    public void on(OrderPlacedEvent event) {
        jdbc.update(
            "INSERT INTO order_summary_view (order_id, customer_name, total_amount, status) "
            + "VALUES (?, ?, ?, 'PLACED')",
            event.getOrderId(), event.getCustomerName(), event.getTotalAmount()
        );
    }
 
    public void on(OrderShippedEvent event) {
        jdbc.update(
            "UPDATE order_summary_view SET status = 'SHIPPED' WHERE order_id = ?",
            event.getOrderId()
        );
    }
}

# 同一数据，不同的读模型服务不同场景
# 列表页读模型（Redis Hash）
class OrderListCache:
    def get_recent_orders(self, customer_id: str, limit: int = 20):
        return self.redis.lrange(f"orders:{customer_id}", 0, limit)
# 搜索读模型（Elasticsearch）
class OrderSearchIndex:
    def search(self, keyword: str, filters: dict):
        return self.es.search(index="orders", query={"match": {"description": keyword}})
# 报表读模型（数据仓库）
class OrderReportView:
    def monthly_sales(self, year_month: str):
        return self.warehouse.query(
            "SELECT SUM(total) FROM sales_fact WHERE month = %s", year_month)