jboner

Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD

patakijv

class ChangeIgnoredToBoolean < ActiveRecord::Migration
  # we should have been using boolean vs string for a flag instead of a string
  def up
    # preserve existing data
    @saved_ignored_state = Message.all.map(&:ignored)
    change_column(:messages, :ignored, :boolean, :default => false)
    Message.reset_column_information
    Message.all.each_with_index do |message,index|
      message.update_attribute(:ignored,@saved_ignored_state[index] == 'true')
    end

jimbojsb

Step 0:

Get Homebrew installed on your mac if you don't already have it

Step 1:

Install highlight. "brew install highlight". (This brings down Lua and Boost as well)

Step 2: