Andrey Novikov Envek

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

Demo:

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Spoiler text. Note that it's important to have a space after the summary tag. You should be able to write any markdown you want inside the <details> tag... just make sure you close <details> afterward.

console.log("I'm a code block!");

YARD CHEATSHEET http://yardoc.org

May 2020 - updated fork: https://gist.github.com/phansch/db18a595d2f5f1ef16646af72fe1fb0e

cribbed from http://pastebin.com/xgzeAmBn

Templates to remind you of the options and formatting for the different types of objects you might want to document using YARD.

	module ObfuscatedId
	extend ActiveSupport::Concern

	# Constants used to obfuscate identifiers with formula id * multipier % modulo
	# modulo and multiplier must be coprime numbers to avoid collisions
	# modulo must be larger than maximum value of id
	MODULO = Rails.application.secrets.id_obfuscation[:modulo]
	EXPONENT = Rails.application.secrets.id_obfuscation[:exponent]
	# Should contain digits and letters common for latin and cyrillic alphabets
	# "12345679AEKMHPCTYX".split('').shuffle.join


	CREATE OR REPLACE FUNCTION jsonb_remove_keys(
	jdata JSONB,
	keys TEXT[]
	)
	RETURNS JSONB AS $$
	DECLARE
	result JSONB;
	len INT;
	target TEXT;

	# Instructions for 4.14 and cuda 9.1
	# If upgrading from 4.13 and cuda 9.0
	$ sudo apt-get purge --auto-remove libcud*
	$ sudo apt-get purge --auto-remove cuda*
	$ sudo apt-get purge --auto-remove nvidia*
	# also remove the container directory direcotory at /usr/local/cuda-9.0/

	# Important libs required with 4.14.x with Cuda 9.X
	$ sudo apt install libelf1 libelf-dev

	#!/usr/bin/env python3
	#
	# Script to toggle between the two last used language in Gnome
	#
	# History:
	#
	# Original script by Jacob Vlijm
	# Saving last language and togging: Vadim Zaliva
	#
	# See also: http://askubuntu.com/questions/871678/how-can-i-quickly-switch-between-two-out-of-multiple-languages

	// Font Smoothie copyright 2013,14,15 Torben Haase <http://pixelsvsbytes.com>
	// Source-URL <https://gist.github.com/letorbi/5177771>
	//
	// Font Smoothie is free software: you can redistribute it and/or modify it under
	// the terms of the GNU Lesser General Public License as published by the Free
	// Software Foundation, either version 3 of the License, or (at your option) any
	// later version.
	//
	// Font Smoothie is distributed in the hope that it will be useful, but WITHOUT
	// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

	module ActiveRecord::UnionScope
	def self.included(base)
	base.send :extend, ClassMethods
	end

	module ClassMethods
	def union_scope(*scopes)
	id_column = "#{table_name}.#{primary_key}"
	sub_query = scopes.map { \|s\| s.select(id_column).to_sql }.join(" UNION ")
	where "#{id_column} IN (#{sub_query})"

	# Some modular arithmetic helper methods useful for number theory or
	# cryptography.
	#
	# # Examples
	#
	# Compute the greatest common denominator of 114 and 48:
	#
	# gcd(114, 48) #=> 6
	#
	# Compute `a` and `b` such that `ax + by = gcd(x, y)`:

Andrey Novikov Envek

Demo:

YARD CHEATSHEET http://yardoc.org

May 2020 - updated fork: https://gist.github.com/phansch/db18a595d2f5f1ef16646af72fe1fb0e

Modules