Dan Kubb dkubb

High level design

In Veritas a relation is an Enumerable object that will yield a set of tuples.
Internally a relation is represented as a tree.
The leaf nodes are base relations, which are the data sources.
There are 3 types of inner nodes:
1. A node may be a relational algebra operation like join, rename, project or others. When iterated it will evaluate it's children, then perform the operation in-memory and yield each tuple

	require 'memoist'

	# Usage:
	#
	# customers = Customer.preload(Customer.orders.line_items.item)
	#
	# customers.each do \|customer\|
	# customer.orders.each do \|order\|
	# order.line_items.each do \|line_item\|
	# line_item.item # yay, no more N+1, only 4 queries executed !

	#!/usr/bin/ruby

	# encoding: utf-8

	require 'pathname'

	paths = ARGV.map { \|arg\| Pathname.glob(arg) }.flatten

	paths.each do \|path_in\|
	start_path = path_in.directory? ? path_in + '*/' : path_in

	#!/opt/local/bin/ruby

	# Copyright (c) 2007, 2011 Dan Kubb <[email protected]>

	require 'rubygems'
	require 'csspool'
	require 'hpricot'
	require 'net/https'
	require 'open-uri'

	# gem install backports veritas veritas-optimizer veritas-do-adapter do_postgres

	require 'pp'
	require 'rational'

	require 'rubygems'
	require 'backports'
	require 'backports/basic_object'
	require 'veritas'
	require 'veritas-optimizer'

	class MyMigration < Veritas::Migration
	def call

	# Transformations
	# ---------------
	# 1) remove all columns except id, name and email
	# 2) rename user_id to id
	# 3) add a boolean active column, setting the default to false
	# 4) add a constraint on name where it must be between 1 and 100 characters

	# Random is available in 1.9 (or 1.8 w/backports)

	def random_routing_number
	digits = Random.new.rand(10_000_000..99_999_999).to_s.split('')

	sum = digits.each_slice(3).inject(0) do \|sum, (d1, d2, d3)\|
	sum + 7 * d1.to_i + 3 * d2.to_i + 9 * d3.to_i
	end

	digits.push(sum % 10).join

	#!/usr/bin/env ruby -Ku

	# encoding: utf-8

	require 'stringio'

	require 'rubygems'
	require 'slim'

	class StreamBuffer < Temple::Generator