Mohammed Sadiq sadiqmmm

PSQL

Magic words:

psql -U postgres

Some interesting flags (to see all, use -h or --help depending on your psql version):

-E: will describe the underlaying queries of the \ commands (cool for learning!)
-l: psql will list all databases and then exit (useful if the user you connect with doesn't has a default database, like at AWS RDS)

Rails 4 is out featuring Russian Doll caching (AKA Cache Digests). In this article, I apply Russian Doll caching to one of my poorer performing Rails 3 pages using the cache_digests gem.

ActionView templates are great. They are easy to code, manage and extend but the one thing they are not is fast...at least not out of the box.

In this article, I'll be using AppNeta's TraceView to time ActionView performance. If you haven't used TraceView before, checkout my previous article Instrumenting Ruby on Rails with TraceView.

ActionView is Slow; Pitfalls Ahead

ActionView puts forth a great development pattern of views and partials that is easy to understand, implement and maintain but that comes at a cost: The rendering process is complex and slow.

	class ApplicationController < ActionController::Base

	private

	# Runs a rake task asyncronously in a child process
	#
	# for example, in any controller:
	# async_rake("async:import_fixtures")
	# async_rake("db:maintenance:cleanup", table: "things", ids: [12, 114, 539])
	#

	class ChangeProductLongDescription < ActiveRecord::Migration
	def up
	# simple and straightforward
	change_column :products, :long_description, :text
	end

	# but why cant it just be:
	# change_column :product, :long_description, :string
	# ???
	# because effin databases don't like you, that's why.

	#!/bin/bash
	### BEGIN INIT INFO
	# Provides: sidekiq beta
	# Required-Start: $syslog $remote_fs
	# Required-Stop: $syslog $remote_fs
	# Should-Start: $local_fs
	# Should-Stop: $local_fs
	# Default-Start: 2 3 4 5
	# Default-Stop: 0 1 6
	# Short-Description: sidekiq beta - asynchronous rails

	# I don't really see any services here. What I see is:
	# - Normal HTTP boundary stuff (params flash, redirect).
	# - Model creation and retrieval.
	# - Warden manipulation, which is an odd done but smells like boundary.
	#
	# I left all of the HTTP boundary stuff in the controller (and only the
	# controller). I moved the model creation/retrieval into simple class methods
	# in the models. I moved the warden manipulation stuff into
	# ApplicationController (with caveats that I'll discuss inline).
	#

	# Ways to execute a shell script in Ruby
	# Example Script - Joseph Pecoraro

	cmd = "echo 'hi'" # Sample string that can be used

	# 1. Kernel#` - commonly called backticks - `cmd`
	# This is like many other languages, including bash, PHP, and Perl
	# Synchronous (blocking)
	# Returns the output of the shell command
	# Docs: http://ruby-doc.org/core/classes/Kernel.html#M001111