Alex Chen alex-nexus

Presto Specific

Don’t SELECT *, Specify explicit column names (columnar store)
Avoid large JOINs (filter each table first)
- In PRESTO tables are joined in the order they are listed!!
- Join small tables earlier in the plan and leave larger fact tables to the end
- Avoid cross joins or 1 to many joins as these can degrade performance
Order by and group by take time
- only use order by in subqueries if it is really necessary
When using GROUP BY, order the columns by the highest cardinality (that is, most number of unique values) to the lowest.

	#!/bin/bash
	for file in *.webp; do
	dwebp -o "`basename $file .webp`.png" "$file"
	done

	<!DOCTYPE html>
	<html lang="en">
	<head>
	<meta http-equiv="Content-type" content="text/html; charset=utf-8" />
	<title>Stripe Getting Started Form</title>

	<!-- The required Stripe lib -->
	<script type="text/javascript" src="https://js.stripe.com/v2/"></script>

	<!-- jQuery is used only for this example; it isn't required to use Stripe -->

	-- show running queries (pre 9.2)
	SELECT procpid, age(clock_timestamp(), query_start), usename, current_query
	FROM pg_stat_activity
	WHERE current_query != '<IDLE>' AND current_query NOT ILIKE '%pg_stat_activity%'
	ORDER BY query_start desc;

	-- show running queries (9.2)
	SELECT pid, age(clock_timestamp(), query_start), usename, query
	FROM pg_stat_activity
	WHERE query != '<IDLE>' AND query NOT ILIKE '%pg_stat_activity%'

	import numpy as np
	import warnings

	from itertools import cycle, izip

	from sklearn.utils import gen_even_slices
	from sklearn.utils import shuffle
	from sklearn.base import BaseEstimator
	from sklearn.base import ClassifierMixin
	from sklearn.preprocessing import LabelBinarizer

	!!! 5
	/[if lt IE 7] <html lang="en" class="no-js ie6">
	/[if IE 7 ] <html lang="en" class="no-js ie7">
	/[if IE 8 ] <html lang="en" class="no-js ie8">
	/[if IE 9 ] <html lang="en" class="no-js ie9">
	<!--[if (gt IE 9)\|!(IE)]><!--> <html lang="en" class="no-js"> <!--<![endif]-->
	%head
	%meta{:charset => "utf-8"}/
	/
	Always force latest IE rendering engine (even in intranet) & Chrome Frame

	class PagesController < ApplicationController
	before_filter :login_required, :except => [ :show ]

	# GET /pages
	# GET /pages.xml
	def index
	@pages = Page.find(:all)

	respond_to do \|format\|
	format.html # index.html.erb