Code Review: N+1 Database Queries

mediumCode ReviewJS / TS

Problem Statement

Review the following user profile enrichment service. Identify performance issues (specifically N+1 database query patterns), explain the architectural impact on database connection pools, and propose an optimized batching/joining solution.

Code under review

JAVASCRIPT• handler.js

Pairlet Snippet

// Service handler fetching active user profiles and their recent orders
async function getUserDashboardData(userIds) {
  const users = [];

  for (const id of userIds) {
    const user = await db.query('SELECT * FROM users WHERE id = $1', [id]);
    const orders = await db.query('SELECT * FROM orders WHERE user_id = $1 ORDER BY created_at DESC LIMIT 5', [id]);
    const settings = await db.query('SELECT * FROM user_settings WHERE user_id = $1', [id]);

    users.push({
      ...user,
      recentOrders: orders,
      settings: settings[0] || {}
    });
  }

  return users;
}

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Code Review: N+1 Database Queries

Problem Statement

Code under review

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