codesnips

performance

sql 
-- Basic EXPLAIN
EXPLAIN
SELECT * FROM users WHERE email = 'alice@example.com';

-- EXPLAIN with cost and row estimates
-- Output shows: Seq Scan on users (cost=0.00..15.50 rows=1 width=100)

EXPLAIN and query plan optimization

sql explain query-optimization
by Maria Garcia 2 tabs
python 
from django.db.models import Prefetch
from django.views.generic import ListView
from .models import Post, Comment


class PostListView(ListView):

Django select_related and prefetch_related for N+1 query optimization

django python performance
by Priya Sharma 1 tab
ruby 
class AddCommentsCountToPosts < ActiveRecord::Migration[6.1]
  def up
    add_column :posts, :comments_count, :integer, default: 0, null: false

    # Populate existing counts
    Post.find_each do |post|

Counter cache for association counts

rails performance activerecord
by Alex Kumar 2 tabs
erb 
<%# Fragment caching - caches rendered HTML %>
<% cache @product do %>
  <h1><%= @product.name %></h1>
  <p><%= @product.description %></p>
  <p>Price: $<%= @product.price %></p>
<% end %>

Rails caching strategies for performance

ruby rails caching
by Sarah Mitchell 4 tabs
ruby 
class CreateCustomerRevenueSummaries < ActiveRecord::Migration[7.0]
  def change
    create_view :customer_revenue_summaries, materialized: true, version: 1

    add_index :customer_revenue_summaries,
              :customer_id,

Database Views for Read Models

rails postgres performance
by codesnips 4 tabs
sql 
-- Create basic index
CREATE INDEX idx_users_email ON users(email);

-- Unique index (enforces uniqueness)
CREATE UNIQUE INDEX idx_users_username ON users(username);

Database indexing strategies for performance

database indexing performance
by Maria Garcia 2 tabs
sql 
CREATE TABLE subscriptions (
    id                  BIGGENERATED ALWAYS AS IDENTITY PRIMARY KEY,
    customer_id         BIGINT       NOT NULL,
    plan_code           TEXT         NOT NULL,
    status              TEXT         NOT NULL DEFAULT 'active',
    current_period_end  TIMESTAMPTZ  NOT NULL,

Partial index for “active” rows in Postgres

postgres performance sql
by codesnips 3 tabs
typescript 
import { SetMetadata } from '@nestjs/common';

export const CACHEABLE_KEY = 'cacheable:options';

export type VaryDimension = 'user' | 'tenant' | 'query';

Per-Route Response Caching in NestJS with a Custom CacheInterceptor and Cache Key Builder

nestjs caching interceptors
by codesnips 4 tabs
javascript 
import { Controller } from "@hotwired/stimulus"

export default class extends Controller {
  static targets = ["sentinel"]
  static values = {
    url: String

Infinite scroll with Turbo Frames and Intersection Observer

hotwire turbo stimulus
by Jordan Lee 3 tabs
typescript 
import { Link } from 'react-router-dom'
import { useQueryClient } from '@tanstack/react-query'
import api from '@/services/api'
import { PostId } from '@/types'

interface PostLinkProps {

Prefetching data on hover for instant navigation

react performance prefetching
by Maya Patel 1 tab
typescript 
import React from 'react'

interface SkeletonProps {
  width?: string | number
  height?: string | number
  className?: string

Skeleton screens for better perceived performance

react ux performance
by Maya Patel 3 tabs
ruby 
module KeysetPaginatable
  extend ActiveSupport::Concern

  class_methods do
    def keyset_page(cursor: nil, limit: 20, direction: :desc)
      limit = limit.to_i.clamp(1, 100)

Keyset Cursor Pagination for ActiveRecord Instead of OFFSET

ruby rails activerecord
by codesnips 4 tabs