Igor Bilan igorb

I'm hunting for the best solution on how to handle keeping large sets of DB records "sorted" in a performant manner.

Problem Description

Most of us have work on projects at some point where we have needed to have ordered lists of objects. Whether it be a to-do list sorted by priority, or a list of documents that a user can sort in whatever order they want.

A traditional approach for this on a Rails project is to use something like the acts_as_list gem, or something similar. These systems typically add some sort of "postion" or "sort order" column to each record, which is then used when querying out the records in a traditional order by position SQL query.

This approach seems to work fine for smaller datasets, but can be hard to manage on large data sets with hundreds (or thousands) of records needing to be sorted. Changing the sort position of even a single object will require updating every single record in the database that is in the same sort group. This requires potentially thousands of wri

Moved to git repository: https://github.com/denji/nginx-tuning

NGINX Tuning For Best Performance

For this configuration you can use web server you like, i decided, because i work mostly with it to use nginx.

Generally, properly configured nginx can handle up to 400K to 500K requests per second (clustered), most what i saw is 50K to 80K (non-clustered) requests per second and 30% CPU load, course, this was 2 x Intel Xeon with HyperThreading enabled, but it can work without problem on slower machines.

You must understand that this config is used in testing environment and not in production so you will need to find a way to implement most of those features best possible for your servers.

JWT Auth + Refresh Tokens in Rails

This is just some code I recently used in my development application in order to add token-based authentication for my api-only rails app. The api-client was to be consumed by a mobile application, so I needed an authentication solution that would keep the user logged in indefinetly and the only way to do this was either using refresh tokens or sliding sessions.

I also needed a way to both blacklist and whitelist tokens based on a unique identifier (jti)

Before trying it out DIY, I considered using:

	$('#search').keyup($.throttle(function() {
	// Will only execute 300ms after the last keypress.
	if ($('#search').val().length > 0) {
	sendSearchAjaxRequest();
	} else {
	$('.search_dropdown').hide()
	}
	}, 300));

	class SearchesController < ApplicationController
	def show
	# 1) User model have a 'title' - an alias to full_name to search by title
	# 2) scope :like_a, -> (title) { where('lower(title) LIKE ?', "%#{title}%")
	# 3) use ActiveModelSerializer: or serialize a specific collection:
	# (ActiveModel::ArraySerializer.new(items, each_serializer: ItemSerializer)) should be like [{ id, title, url }]

	render json: SearchServices.new(current_user, title).results
	end

	<?xml version="1.0" encoding="UTF-8"?>
	<!--
	Licensed to the Apache Software Foundation (ASF) under one or more
	contributor license agreements. See the NOTICE file distributed with
	this work for additional information regarding copyright ownership.
	The ASF licenses this file to You under the Apache License, Version 2.0
	(the "License"); you may not use this file except in compliance with
	the License. You may obtain a copy of the License at

	http://www.apache.org/licenses/LICENSE-2.0

	require 'csv'

	file = "#{Rails.root}/public/data.csv"

	table = User.all;0 # ";0" stops output. Change "User" to any model.

	CSV.open( file, 'w' ) do \|writer\|
	writer << table.first.attributes.map { \|a,v\| a }
	table.each do \|s\|
	writer << s.attributes.map { \|a,v\| v }

	assets_path = File.expand_path("~/projects/rails/scout/public")
	log_path = File.expand_path "~/assets.txt"
	temp_requested_files_path = File.expand_path "~/processed_assets.txt"
	ignore_pattern = /sparkline\|datejs/

	known_used =[
	"javascripts/jquery-1.7.1.min.js",
	"javascripts/jquery.extensions.js",
	"javascripts/application.js",
	"stylesheets/default.css",

	columns_that_make_record_distinct = [:some_id, :another_name]
	distinct_ids = Model.select("MIN(id) as id").group(columns_that_make_record_distinct).map(&:id)

	duplicate_records = Model.where.not(id: distinct_ids)

	SELECT
	tc.constraint_name, tc.table_name, kcu.column_name,
	ccu.table_name AS foreign_table_name,
	ccu.column_name AS foreign_column_name
	FROM
	information_schema.table_constraints AS tc
	JOIN information_schema.key_column_usage AS kcu
	ON tc.constraint_name = kcu.constraint_name
	JOIN information_schema.constraint_column_usage AS ccu
	ON ccu.constraint_name = tc.constraint_name