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The master method for solving recurrences

24 Aug 2022

1. Mathematical Induction Principle of Mathematical Induction: Let P be a property of positive integers such that: Basis step: P(1) is true, and Inductive step: if P(k) is true for all 1 ≤ k ≤ n then P(n + 1) is true. Then P(n) is true for all positive integers....
Designing Data-Intensive Applications: Stream Processing

10 Aug 2022

In reality, a lot of data is unbounded because it arrives gradually over time: your users produced data yesterday and today, and they will continue to produce more data tomorrow. Unless you go out of business, this process never ends, and so the dataset is never “complete” in any meaningful...
Designing Data-Intensive Applications: Consistency and Consensus

09 Aug 2022

The simplest way of handling faults in distributed systems is to simply let the entire service fail, and show the user an error message. If that solution is unacceptable, we need to find ways of tolerating faults—that is, of keeping the service functioning correctly, even if some internal component is...
Designing Data-Intensive Applications: The Trouble with Distributed Systems

08 Aug 2022

1. Faults and Partial Failures When you are writing a program on a single computer, it normally behaves in a fairly predictable way: either it works or it doesn’t. Buggy software may give the appearance that the computer is sometimes “having a bad day” (a problem that is often fixed...
Designing Data-Intensive Applications: Database Transactions

08 Aug 2022

1. The Meaning of ACID The safety guarantees provided by transactions are often described by the wellknown acronym ACID, which stands for Atomicity, Consistency, Isolation, and Durability. It was coined in 1983 by Theo Härder and Andreas Reuter in an effort to establish precise terminology for fault-tolerance mechanisms in databases....
Designing Data-Intensive Applications: B-Trees and LSM-Trees

07 Aug 2022

Consider the world’s simplest database, implemented as two Bash functions: #!/bin/bash db_set () { echo "$1,$2" >> database } db_get () { grep "^$1," database | sed -e "s/^$1,//" | tail -n 1 } These two functions implement a key-value store. You can call db_set key value, which will store...
Introduction to Reactive Programming

14 Jun 2022

1. Introduction to Reactive Programming Reactor is an implementation of the Reactive Programming paradigm, which can be summed up as follows: Reactive programming is an asynchronous programming paradigm concerned with data streams and the propagation of change. This means that it becomes possible to express static (e.g. arrays) or dynamic...
How to run docker on remote host on Windows

06 Jun 2022

I have a Linux VM running on my Windows desktop. This post will explain how to access the docker server at Linux on Windows. 1. Set dockerd to listen on mutliple hosts. Configure docker daemon.json to support mutliple hosts. { "exec-opts": ["native.cgroupdriver=systemd"], "log-driver": "json-file", "log-opts": { "max-size": "100m" }, "data-root":...
What is OAuth2

21 May 2022

1. What is OAuth2 In the traditional client-server authentication model, the client requests an access-restricted or protected resource on the server by authenticating with the server using the resource owner’s credentials. [RFC6749] In order to provide third-party applications access to restricted resources, the resource owner shares its credentials with the...
Intro to PostgreSQL

20 May 2022

1. What Is PostgreSQL PostgreSQL is an object-relational database management system (ORDBMS) based on POSTGRES, Version 4.2, developed at the University of California at Berkeley Computer Science Department. POSTGRES pioneered many concepts that only became available in some commercial database systems much later. [1] PostgreSQL is an open-source descendant of...
Scala in Action

01 May 2022

1. First Steps in Scala 1.1. Learn to use the Scala interpreter The easiest way to get started with Scala is by using the Scala interpreter, an interactive “shell” for writing Scala expressions and programs. Simply type an expression into the interpreter and it will evaluate the expression and print...
Network Latency vs. Throughput vs. Bandwidth

08 Mar 2022

Use qperf to measure network throughput and latency # install qperf sudo apt-get install qperf # run qperf on one node in server mode by invoking it with no arguments qperf # run qperf on a client node to obtain measurements such as bandwidth, latency qperf -ip 19766 -t 10...
Overview of Linux Kernel Security Features

11 Feb 2022

Editor’s Note: This is a guest post from James Morris, the Linux kernel security subsystem maintainer and manager of the mainline Linux kernel development team at Oracle. In this article, we’ll take a high-level look at the security features of the Linux kernel. We’ll start with a brief overview of...
Kubernetes Logging

07 Jan 2022

1. Kubernetes Logging In a Kubernetes cluster, logs should have a separate storage and lifecycle independent of nodes, pods, or containers, that is called cluster-level logging. [1] 1.1. Pod and container logs Kubernetes captures logs from each container in a running Pod. # debug/counter-pod.yaml apiVersion: v1 kind: Pod metadata: name:...
Kubernetes Securitycontext, User and Group

31 Dec 2021

1. USER instruction at Dockerfile The USER instruction sets the user name (or UID) and optionally the user group (or GID) to use when running the image and for any RUN, CMD and ENTRYPOINT instructions that follow it in the Dockerfile. $ docker run --rm -it debian:11 id uid=0(root) gid=0(root)...
What is MySQL?

29 Dec 2021

1. Deploying MySQL on Linux with Docker 1.1. Starting a MySQL Server Instance To start a new Docker container for a MySQL Server, use the following command: docker run --name=container_name [--restart on-failure] -d -e MYSQL_RANDOM_ROOT_PASSWORD=yes [-e MYSQL_ONETIME_PASSWORD=yes] image_name:tag $ docker run --name mysql8 -d -e MYSQL_RANDOM_ROOT_PASSWORD=yes mysql:8 b4b86043b5562bb9069d82a663e2beae7fb417d6c3a005ade1a9b48ced6048f5 $ docker...

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