# BAD: N+1 query problem
@users = User.all
@users.each do |user|
puts user.posts.count # Fires query for each user!
end
-- EXPLAIN ANALYZE (actual execution statistics)
EXPLAIN ANALYZE
SELECT u.username, COUNT(o.id) AS order_count
FROM users u
LEFT JOIN orders o ON u.id = o.user_id
WHERE u.created_at >= '2024-01-01'
package com.example.myapp.utils
import android.os.Build
import android.os.StrictMode
import android.os.Trace
import timber.log.Timber
const withBundleAnalyzer = require('@next/bundle-analyzer')({
enabled: process.env.ANALYZE === 'true',
openAnalyzer: true,
});
/** @type {import('next').NextConfig} */
use std::borrow::Cow;
fn ensure_prefix(input: &str) -> Cow<str> {
if input.starts_with("https://") {
Cow::Borrowed(input)
} else {
module WriteAmplificationGuard
extend ActiveSupport::Concern
def update_if_changed(attrs)
changed = attrs.each_with_object({}) do |(key, value), acc|
cast = self.class.type_for_attribute(key.to_s).cast(value)
Rails.application.configure do
# Bullet configuration
config.after_initialize do
Bullet.enable = true
Bullet.alert = true # Show JavaScript alert
Bullet.bullet_logger = true # Log to bullet.log
// Creating elements
const div = document.createElement('div');
div.id = 'container';
div.className = 'box rounded';
div.textContent = 'Hello World';
-- SCHEMA DESIGN CHECKLIST
-- 1. Use appropriate data types
CREATE TABLE users_optimized (
id SERIAL PRIMARY KEY, -- Auto-increment
uuid UUID DEFAULT gen_random_uuid(), -- UUID for external IDs
FROM node:20-alpine AS base
WORKDIR /app
RUN apk add --no-cache libc6-compat
FROM base AS deps
COPY package.json package-lock.json ./
# Gemfile
group :development do
gem 'rack-mini-profiler'
gem 'memory_profiler'
gem 'stackprof' # For flamegraphs
gem 'bullet' # N+1 detection
# Optimized production Dockerfile
# Stage 1: Dependencies
FROM node:20-alpine AS deps
WORKDIR /app