scart88

In my application every time I send a newsletter to a User, I create a NewsletterDelivery record. I frequently want to be able to query, for each user, what is the most recent newsletter delivery record. This is called a "last n per group" query and a LATERAL JOIN is the best way to do it imo. But the query I've been using (and I've told people to use, and seen blogged about) is not very good, because the conditions don't get pushed down into the subselect which means that the query ends-up lateral-joining all the records before it applies the conditions for the association.

Instead of doing subselect_table.* the better query does association.id AS assocation_id, subselect_table.id, subselect_table.title, .... and enumerates over all of the columns. This allows the association query, which Active Record tacks on at the end as WHERE association_id = $1 or WHERE association_id IN ($1, $2, $3, ...) to be pushed down c

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queue = Sidekiq::Queue.new("default")

queue.each do |job|
  if job.klass == "DailyFrequencyCreatorWorker"
    DailyFrequencyCreatorWorker.set(queue: 'daily_frequency_creator').perform_async(*job.args)

    job.delete
  end
end;nil

scart88

How to think about asof queries.

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1. pg_dump is a nifty utility designed to output a series of SQL statements that describes the schema and data of your database. You can control what goes into your backup by using additional flags.
   Backup: pg_dump -h localhost -p 5432 -U postgres -d mydb > backup.sql

   Restore: psql -h localhost -p 5432 -U postgres -d mydb < backup.sql

   -h is for host.
   -p is for port.
   -U is for username.
   -d is for database.

scart88

MRSK

This documentation adds important additions to the docs for mrsk deploy tool (see github.com/mrsked/mrsk)

Destination flag

You can use mrsk deploy --destination staging

This will read config/deploy.yml and config/deploy.staging.yml files, and also will read .env.staging file if it exists.

scart88

# UFW Commands to make your life eaiser

# Install UFW
sudo apt-get update
sudo apt-get install ufw

# View UFW Status
sudo ufw status

# Enable UFW

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Install WireGuard via whatever package manager you use.  For me, I use apt.

$ sudo add-apt-repository ppa:wireguard/wireguard
$ sudo apt-get update
$ sudo apt-get install wireguard

MacOS
$ brew install wireguard-tools

Generate key your key pairs.  The key pairs are just that, key pairs.  They can be

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module ApplicationHelper

  def current_class?(test_path)
    return 'active' if request.path == test_path
    ''
  end

end

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# http://stackoverflow.com/questions/4397412/read-edit-and-write-a-text-file-line-wise-using-ruby
# files = Dir.glob(File.dirname(__FILE__)+"/../app/**/*.rb")
files = Dir[Rails.root.join("app", "**/*.rb")]

files.each do |f_name|
  # puts f_name
  File.open(f_name, "r+") do |f|

    old_pos = 0
    f.each do |line|

scart88

require 'nokogiri'
require 'open-uri'

#Scrapes img alt tags from specified URL 
url = "CHANGE ME"
alt_tags = Array.new
doc = Nokogiri::HTML(open(url))
alt_tags = doc.css('img').map{ |i| i['alt'] } 

#Prints out unique alt tags