August 2024
Intermediate to advanced
392 pages
10h 4m
Japanese
Content preview from 達人に学ぶDB設計徹底指南書 第2版
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すなわちデータマートは、全社的な情報を含むセントラル・データウェアハウス
から切り出したより小規模で各部門のユーザーが利用しやすい形に加工したテーブ
ル群、ということです。典型的には様々な部門・部署が利用する帳票やレポートを
出力しやすい形に整形されたテーブルを指します。ウェアハウスが「倉庫」、マー
トが（エンドユーザーが買い物をする）「市場」と考えるとイメージしやすいでしょう。
データマートが必要とされる理由は主に二つです。一つは、
です。セントラルDWH は非常に多くの部門から集めた雑多なデータを保持してい
ることが多いため、一つの特定の部門が欲しいデータをすぐに見つけにくく、巨大
すぎて扱いづらいという性質を持っています。こうした DWH からサブセットを切
り出して部門ごとに利用しやすいテーブルを用意してあげるのがデータマートの
必要とされる理由の一つ目です。二つ目の理由はです。セントラ
ル DWH は非常に巨大なファクトテーブルを核に持っているため、帳票出力やアド
ホックな集計のたびにそれにアクセスしていたのではクエリが遅くて使い物になら
ないことが多いのです。そのため、より小規模なサブセットであるデータマートを
用意することで性能向上を図る目的があります。
いわばデータマートは、第1 章で学習した外部スキーマ（ビュー）に相当するも
のなのです。ビューもデータマートも直接ユーザーが操作可能ですし、 ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
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.