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PostgreSQL is Enough

https://www.postgresql.org

https://sive.rs/pg

Background Jobs

• https://github.com/citusdata/pg_cron

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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

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##TCP FLAGS##

Unskilled Attackers Pester Real Security Folks
==============================================
                     TCPDUMP FLAGS
Unskilled =  URG  =  (Not Displayed in Flag Field, Displayed elsewhere) 
Attackers =  ACK  =  (Not Displayed in Flag Field, Displayed elsewhere)
Pester    =  PSH  =  [P] (Push Data)
Real      =  RST  =  [R] (Reset Connection)
Security  =  SYN  =  [S] (Start Connection)

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Markdown and reStructuredText

GitHub supports several lightweight markup languages for documentation; the most popular ones (generally, not just at GitHub) are Markdown and reStructuredText. Markdown is sometimes considered easier to use, and is often preferred when the purpose is simply to generate HTML. On the other hand, reStructuredText is more extensible and powerful, with native support (not just embedded HTML) for tables, as well as things like automatic generation of tables of contents.

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The reStructuredText_ Cheat Sheet: Syntax Reminders

Info:	See <http://docutils.sf.net/rst.html> for introductory docs.
Author:	David Goodger <goodger@python.org>
Date:	2013-02-20
Revision:	7612
Description:	This is a "docinfo block", or bibliographic field list

Note

If you are reading this as HTML, please read

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package fpmax

import scala.util.Try
import scala.io.StdIn.readLine

object App0 {
  def main: Unit = {
    println("What is your name?")

    val name = readLine()

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Thread Pools

Thread pools on the JVM should usually be divided into the following three categories:

1. CPU-bound
2. Blocking IO
3. Non-blocking IO polling

Each of these categories has a different optimal configuration and usage pattern.

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Applied Functional Programming with Scala - Notes

Copyright © 2016-2018 Fantasyland Institute of Learning. All rights reserved.

1. Mastering Functions

A function is a mapping from one set, called a domain, to another set, called the codomain. A function associates every element in the domain with exactly one element in the codomain. In Scala, both domain and codomain are types.

val square : Int => Int = x => x * x

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package controllers

import java.io.File
import javax.inject.Inject

import play.api.Logger
import play.Environment
import play.api.mvc.{Action, AnyContent}
import play.mvc.Controller

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package controllers.staticAssets

import play.api.http.HeaderNames
import play.api.mvc.{Action, Request, Result}

import scala.concurrent.Future

case class AddNoCacheHeaders[A](action: Action[A]) extends Action[A] with HeaderNames {
  def apply(request: Request[A]): Future[Result] = {
    import scala.concurrent.ExecutionContext.Implicits.global