提高用于查询GraphQL连接的SQL代码的性能

const DataLoader = require('dataloader');

// 创建一个数据加载器实例
const userLoader = new DataLoader(async (userIds) => {
  const users = await db.users.find({ id: { $in: userIds } });
  return userIds.map(id => users.find(user => user.id === id));
});

// 在解析器中使用数据加载器
const resolvers = {
  Query: {
    user: (_, { id }) => userLoader.load(id),
  },
};

-- 使用索引优化查询
CREATE INDEX idx_user_id ON orders(user_id);

-- 避免复杂的JOIN操作，尽量减少连接的数量
SELECT u.*, o.*
FROM users u
JOIN orders o ON u.id = o.user_id
WHERE u.id = ?;

const usersWithOrders = await db.users.findAll({
  include: [{
    model: db.orders,
    where: { status: 'completed' }
  }]
});

const NodeCache = require('node-cache');
const cache = new NodeCache();

const getUser = async (id) => {
  const cachedUser = cache.get(`user:${id}`);
  if (cachedUser) return cachedUser;

  const user = await db.users.findByPk(id);
  cache.set(`user:${id}`, user, 60); // 缓存60秒
  return user;
};