Michael Fairchild fairchild

Preamble

On OS/X Sierra, after recently running a brew update I started receiving the error message Sorry, you can't use byebug without Readline when trying to run some rake tasks in my ruby project folder. I observed this in projects and gems that include byebug or pry in their Gemfile or gem.spec. I've found in my googling that many begin encountering this error message after running a brew update but there are other triggering conditions as well.

>> rake aws:show_config
WARN: Unresolved specs during Gem::Specification.reset:
      mime-types (>= 0)
WARN: Clearing out unresolved specs.
Please report a bug if this causes problems.
 Sorry, you can't use byebug without Readline. To solve this, you need to

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?

I really liked @tjvantoll article Handling Failed HTTP Responses With fetch(). The one thing I found annoying with it, though, is that response.statusText always returns the generic error message associated with the error code. Most APIs, however, will generally return some kind of useful, more human friendly message in the body.

Here's a modification that will capture this message. The key is that rather than throwing an error, you just throw the response and then process it in the catch block to extract the message in the body:

fetch("/api/foo")
  .then( response => {
    if (!response.ok) { throw response }
    return response.json()  //we only get here if there is no error
 })

Optimizing postgresql table for more than 100K inserts per second

Create UNLOGGED table. This reduces the amount of data written to persistent storage by up to 2x.
Set WITH (autovacuum_enabled=false) on the table. This saves CPU time and IO bandwidth on useless vacuuming of the table (since we never DELETE or UPDATE the table).
Insert rows with COPY FROM STDIN. This is the fastest possible approach to insert rows into table.
Minimize the number of indexes in the table, since they slow down inserts. Usually an index on time timestamp with time zone is enough.
Add synchronous_commit = off to postgresql.conf.
Use table inheritance for fast removal of old data:

Basic

import code; code.interact(local=locals())

Advanced

IPython with embed()

	#!/usr/bin/env ruby
	#
	# Example Ruby CLI script to retrieve worker data from Workday
	# Call on command line with worker id; prints worker name
	# add "request" or "response" after worker id and prints the
	# outgoing xml or received hash and exits.
	#
	# Using Savon version 2 for the SOAP client (2.11.2)
	#
	# Savon defaults to making the message tag the same as the operation name

	# Add to `spec/support/database_state_loader.rb`

	class DatabaseStateLoader
	class EnvironmentError < RuntimeError; end

	def self.load(path)
	new(path).load
	end

	def initialize(path)

	kind: StorageClass
	apiVersion: storage.k8s.io/v1beta1
	metadata:
	name: fast
	provisioner: kubernetes.io/gce-pd
	parameters:
	type: pd-ssd

	/NPS ROLLING 30-DAYS AVG AND DAILY SCORE CHART/
	SELECT a.date,
	a.net_promoters / a.responses * 100 AS score,
	(SUM(b.net_promoters)
	/
	SUM(b.responses)) * 100 AS score_30d
	FROM (
	SELECT date(s.created_at) AS date,
	SUM(CASE WHEN s.score >= 9 THEN 1.0
	WHEN s.score <= 6 THEN -1.0

	DROP TABLE if exists d_date;

	CREATE TABLE d_date
	(
	date_dim_id INT NOT NULL,
	date_actual DATE NOT NULL,
	epoch BIGINT NOT NULL,
	day_suffix VARCHAR(4) NOT NULL,
	day_name VARCHAR(9) NOT NULL,
	day_of_week INT NOT NULL,