January 2021
Intermediate
240 pages
5h 32m
Japanese
Content preview from 図解まるわかり データベースのしくみ
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42
2-6
NoSQLデータベースの種類①
～キーとバリューを組み合わせたモデル～
NoSQLと呼ばれるデータベースは、データの方式によっていくつかの種
類に分類されます。ここでは参考までにいくつかのモデルを紹介します。
キーバリュー型
キーバリュー型は、キーとバリューの2 つのデータをペアにしたも
のを格納していくことができるモデルです（図 2-13）。バリューには
記録したい情報、キーにはその情報を識別する値を格納します。
例えば、キーに今日の日付、バリューに気温や湿度などの情報を登
録していくと、後からキーである日付をもとにして、バリューに登録
した気候の情報を取得できます。このように、メインとなる値とそれ
を識別するための2 つの値からできている情報をどんどん格納してい
くことができ、キーをもとにして情報を素早く取り出したいときに最
適なモデルです。
です。キーバリュー型が用いられている例として、アクセス履
歴やショッピングカート、ページのキャッシュなどが挙げられます。
カラム指向型
カラム指向型は、キーバリュー型を拡張したようなデータ構造で、
1 つの行を識別するキーに対して、複数のキーとバリューのセットを
持つことができるようになっているモデルです（図2-14）。
1 行に対して複数の列（カラム）がある構造なのでリレーショナル
型と似ていますが、列の名前や数が固定されているわけではなく、 ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.