indexing

class AddSettingsToAccounts < ActiveRecord::Migration[7.1]
  disable_ddl_transaction!

  def change
    add_column :accounts, :settings, :jsonb, null: false, default: {}

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)

CREATE TABLE posts (
    id           bigint GENERATED ALWAYS AS IDENTITY PRIMARY KEY,
    author_id    bigint NOT NULL REFERENCES authors (id),
    title        text   NOT NULL,
    body         text   NOT NULL,
    published_at timestamptz NOT NULL DEFAULT now()

-- Create table with tsvector column
CREATE TABLE articles (
  id SERIAL PRIMARY KEY,
  title VARCHAR(200),
  content TEXT,
  author VARCHAR(100),

class Article < ApplicationRecord
  scope :ranked, -> { order(score: :desc, id: :desc) }

  scope :after_cursor, ->(cursor) do
    return all if cursor.nil?

module KeysetPageable
  extend ActiveSupport::Concern

  included do
    scope :keyset_page, ->(cursor: nil, per: 20) do
      per = per.to_i.clamp(1, 100)

CREATE TABLE daily_events (
    id          BIGSERIAL PRIMARY KEY,
    category    TEXT        NOT NULL,
    item_id     BIGINT      NOT NULL,
    score       NUMERIC(10,2) NOT NULL DEFAULT 0,
    occurred_at TIMESTAMPTZ NOT NULL DEFAULT now()

import pandas as pd

df = pd.read_csv(
    'orders.csv',
    parse_dates=['created_at'],
    dtype={

CREATE TABLE daily_metrics (
    id          BIGGENERATED ALWAYS AS IDENTITY PRIMARY KEY,
    tenant_id   BIGINT      NOT NULL,
    metric      TEXT        NOT NULL,
    day         DATE        NOT NULL,
    count       BIGINT      NOT NULL DEFAULT 0,

-- Create basic index
CREATE INDEX idx_users_email ON users(email);

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

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,

-- Create table with JSONB column
CREATE TABLE users (
  id SERIAL PRIMARY KEY,
  email VARCHAR(255) NOT NULL,
  name VARCHAR(255),
  metadata JSONB DEFAULT '{}'::jsonb