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InnoDB is one of the MySQL storage engine. Likely, it’s the most well-known, the most used, and the most popular one in MySQL storage engines. It’s even the default one when using MySQL.

In this article, I will try to describe what will happen when you execute queries on MySQL with InnoDB.

Why is this article written?

When you are using MySQL as an application developer, you might not need to know the internal architecture of it. Usually there are only a few things which you must know:

Colorize kubectl output by kubecolor


kubectl command is a CLI client of Kubernetes. If you are an administrator of your company’s Kubernetes cluster or a developer who makes an application which runs on Kubernetes, you will be using kubectl almost every day. And I am also one of them.

While kubectl is already good, I have had a pain about its behavior. kubectl’s output is sometimes not easy to read because of its lack of color. Because kubectl sometimes outputs something very long, it is difficult to find what you are looking for.

kubecolor is my new open source CLI…

From: Flickr, no modifications are made.

In distributed systems, sometimes we need to choose only one leader from some nodes. Choosing a leader is the same as granting a special privilege to the node. The process to choose a leader is often called Leader Election. The goal of leader election is that after leader election, every nodes, of course including the leader itself, knows exactly who is a leader.

Why do we want a leader?

Leader is basically expected to do some tasks which should be executed only once. Let’s say there are 3 processes. Now we want to send some WRITE requests to this distributed system. After the request, these WRITE…

From: Flickr

Hi there! Thank you for reading through my series of posts — Let’s study distributed systems. In my previous post, I wrote things about clock.

In this article, I am going to write something about distributed snapshots. First, let’s study what distributed snapshots is, and how it works. Then, let’s take a look in how we can use it.

What is distributed snapshots?

The problem is set like “How to capture current global state of a distributed systems”. Global state is the state of whole distributed system. …

From: Flickr

Did you read my previous post — Let’s study distributed systems 1. Introduction? I tried to tell you some introduction to distributed systems.

In this article, I want to talk about clock. In our daily life, many things are based on time. When we meet our friends, when a train starts… but it assumes that we are sharing the same clock.

Clocks are not accurate

Most clocks in this world are not accurate. Even if it is a radio clock, it doesn’t guarantee that the clock is perfectly accurate. Radio clock uses radio time signal internally, but its speed is the same as light…

Imagine, what will happen when you are running your company by yourself? You can proceed your work by yourself, without any friction with other people. But you have to do everything by yourself. If you hire employees, you can pass some of your tasks to them. However, you have to tell them how to work on it, what you are expecting. Sometimes, you will have to wait for their work. There is no guarantee that they finish their work until deadline you told.

The difference between centralized systems and distributed systems is very similar to above example. We try to…

Hidetatsu YAGINUMA

Hidetatsu loves infrastructures, database, concurrent programming, transactions, distributed systems…

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