jboner

Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD

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

rondy

FWIW: I (@rondy) am not the creator of the content shared here, which is an excerpt from Edmond Lau's book. I simply copied and pasted it from another location and saved it as a personal note, before it gained popularity on news.ycombinator.com. Unfortunately, I cannot recall the exact origin of the original source, nor was I able to find the author's name, so I am can't provide the appropriate credits.

---

Effective Engineer - Notes

• By Edmond Lau
• Highly Recommended 👍
• http://www.theeffectiveengineer.com/

What's an Effective Engineer?

brandonb927

DOMAIN='brandonb.ca'; curl http://web.archive.org/cdx/search/cdx\?limit\=1\&url\=$DOMAIN | awk '{ print $2 }' | xargs date -j -f "%Y%m%d%H%M%S"

brandonb927

#!/bin/bash

#Scaling
#- Scale can be used as is which will set the height to 560 but keep aspect ratio for width.
#- Other options include setting both with & height
#- Watch out for sizing errors when not divisible by 2

if [[ ! "$1" || ! "$2" || ! "$3" ]] || [[ "$1" = '--help' ]]; then
	if [[ "$1" = '--help' ]]; then
		echo " "

brandonb927

#!/bin/sh

###
# SOME COMMANDS WILL NOT WORK ON macOS (Sierra or newer)
# For Sierra or newer, see https://github.com/mathiasbynens/dotfiles/blob/master/.macos
###

# Alot of these configs have been taken from the various places
# on the web, most from here
# https://github.com/mathiasbynens/dotfiles/blob/5b3c8418ed42d93af2e647dc9d122f25cc034871/.osx

sanchezzzhak

SELECT table,
    formatReadableSize(sum(bytes)) as size,
    min(min_date) as min_date,
    max(max_date) as max_date
    FROM system.parts
    WHERE active
GROUP BY table

jamesbar2

[{
    "Note": "The first two digits (ranging from 10–43) correspond to the province, while the last two digits correspond either to the city/delivery zone (range 01–50) or to the district/delivery zone (range 51–99). Afghanistan Postal code lookup",
    "Country": "Afghanistan",
    "ISO": "AF",
    "Format": "NNNN",
    "Regex": "^\\d{4}$"
}, {
    "Note": "With Finland, first two numbers are 22.",
    "Country": "Åland Islands",
    "ISO": "AX",

wavezhang

wget -c --no-cookies --no-check-certificate --header "Cookie: oraclelicense=accept-securebackup-cookie"  https://download.oracle.com/otn-pub/java/jdk/12.0.2+10/e482c34c86bd4bf8b56c0b35558996b9/jdk-12.0.2_linux-x64_bin.tar.gz

momer

There are a number of good introductory SQL resources available for free and online. There are also some paid resources which I recommend for beginners, that are very effective, and well worth expensing in my opinion.

A couple of notes:

• I haven’t used all of these resources, but they come with strong recommendations around the web or myself/my peers.
• You absolutely don’t need to use every single resource. Find a couple that work for you, and go to town.
• You can always reach out to me if you have questions. I always paste this online when people are new to asking very technical questions – it’s not meant to be snarky – it's a gentle guide on how to compose your questions and gather necessary resources in order to best give technical people the information needed to get a quick/effective response: http://www.mikeash.com/getting_answers.html

Video/Class/Mini-course based:

1. Stanford Self-paced ‘Database’ course

• The original Coursera