phund

Setting up and installing rbenv, ruby-build, rubies, rbenv-gemset, and bundler

This guide enables you to install (ruby-build) and use (rbenv) multiple versions of ruby, isolate project gems (gemsets and/or bundler), and automatically use appropriate combinations of rubies and gems.

TL;DR Demo

# Ensure system is in ship-shape.

aptitude install git zsh libssl-dev zlib1g-dev libreadline-dev libyaml-dev

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)

	For bundler I did the following on Catalina

	$ brew install [email protected]
	$ bundle config build.libv8 --with-system-v8
	$ bundle config build.therubyracer --with-v8-dir=$(brew --prefix [email protected])
	$ bundle install

	def cal_retry_time(retry_count)
	time = 0
	(1..retry_count).each do \|rc\|
	time += ((rc ** 4) + 15 + (rand(30) * (rc + 1)))
	end
	p "time: #{time}s => #{time.to_f/3600}h => #{time.to_f/3600/24}day(s)"
	end
	cal_retry_time(10)

	defaults: &defaults
	URL: https://example.com

	development:
	<<: *defaults

	test:
	<<: *defaults

	staging:

	namespace :syntax do

	desc 'Checks the syntax of ERB files'
	task :erb do
	require 'action_view'
	puts "Start check ERB files: "

	errors = []
	Dir['app/views/*/.erb'].each do \|file\|
	template = File.read(file)

	ab \
	-n 1000 \
	-c 20 \
	-s 30 \
	-p post-data.txt \
	-T 'application/x-www-form-urlencoded; charset=UTF-8' \
	-v 3 \
	-H "X-Requested-With: XMLHttpRequest" \
	-H "X-Ajax-Referer: http://example.com" \
	-H "Accept-Encoding: gzip, deflate" \

	-- when you have a record which looks like this
	--
	-- id: 5,
	-- properties: {
	-- ages: [20, 30]
	-- }
	--
	-- it is a bit of a pain if you need to query based on the contents of the "ages" array inside the JSON object "properties"
	-- because PG currently lacks easy to use operators to work with JSON arrays

	require 'active_record'
	require 'activerecord-import'
	require 'benchmark'
	require 'pg'

	include ActiveRecord

	Base.establish_connection adapter: 'postgresql',
	encoding: 'unicode',
	pool: 5,