thanhtruong1216

Question 1

Given an ActiveRecord model (https://gist.github.com/ancv1990/e72a0662d62959cf0ab4947cbc7918b3). How to optimize so that the method User#exists? get the best performance event with millions of record *

# == Schema Information
#
# Table name: users
#
#  id     : integer          not null, primary key