mansueli

Testing RLS policies

To test policies on the database itself (i.e., from the SQL Editor or from psql) without switching to your frontend and logging in as different users, you can utilize the following helper SQL procedures (credits):

grant anon, authenticated to postgres;

create or replace procedure auth.login_as_user (user_email text)
    language plpgsql
    as $$

tennisonchan

Image Optimization: Beyond The Basics

https://www.youtube.com/watch?v=hQZ7Xg7q7zw

Images are by far the greatest bottleneck to performance on the web, and with the average web page size now about 2.5MB large—images taking up 65% of that.

WebP is a new image format which is smallest and provdes either lossless or lossy compression.

<img
 src="dog-800w.jpg" alt="A dog"

dmmiller612

import tensorflow as tf
import numpy as np
from google.protobuf import json_format
import json

np.random.seed(12345)


def tensorflow_get_weights():
    """

vasanthk

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

1. Clarify and agree on the scope of the system

• User cases (description of sequences of events that, taken together, lead to a system doing something useful)
  • Who is going to use it?
  • How are they going to use it?

fphilipe

CREATE EXTENSION btree_gist;

CREATE TABLE room_reservations (
    room_id integer,
    reserved_at timestamptz,
    reserved_until timestamptz,
    canceled boolean DEFAULT false,
    EXCLUDE USING gist (
        room_id WITH =, tstzrange(reserved_at, reserved_until) WITH &&
    ) WHERE (not canceled)

paulirish

/* bling.js */

window.$ = document.querySelectorAll.bind(document);

Node.prototype.on = window.on = function (name, fn) {
  this.addEventListener(name, fn);
}

NodeList.prototype.__proto__ = Array.prototype;

dergachev

OS X Screencast to animated GIF

This gist shows how to create a GIF screencast using only free OS X tools: QuickTime, ffmpeg, and gifsicle.

Instructions

To capture the video (filesize: 19MB), using the free "QuickTime Player" application:

trcarden

# SSL self signed localhost for rails start to finish, no red warnings. 

# 1) Create your private key (any password will do, we remove it below)

$ openssl genrsa -des3 -out server.orig.key 2048


# 2) Remove the password

$ openssl rsa -in server.orig.key -out server.key

hellerbarde

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

zhengjia

=Navigating=
    visit('/projects')
    visit(post_comments_path(post))

=Clicking links and buttons=
    click_link('id-of-link')
    click_link('Link Text')
    click_button('Save')
    click('Link Text') # Click either a link or a button
    click('Button Value')