August 2015
Intermediate to advanced
312 pages
7h 28m
Japanese
Content preview from 初めてのSpark
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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.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.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.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.
217
10.7 ストリーミングの UI
データが再処理されたとしても、変換の最終的な結果（すなわち変換された
RDD
）は、そのデー
タが厳密に
1
度だけ処理された場合と同じになります。
とはいえ、変換された結果が出力操作によって外部のシステムに送出される場合、結果の送出を
行うタスクが障害のために複数回実行され、一部のデータが複数回送出されてしまうことがあり得
ます。この問題には外部のシステムが関わっているため、対処はシステム固有のコードで行わなけ
ればなりません。それには、外部のシステムへの送出にトランザクションを使う（すなわち、
1
つ
の
RDD
のパーティションの送出を
1
回でアトミックに行う）ことや、更新処理が冪等な操作にな
るように設計する（更新が複数回行われても生成される結果が同じになるようにする）といったこ
とが考えられます。例えば
Spark Streaming
の
saveAs...File
操作は、ファイルの生成が完了し
た時点でそのファイルを最終的な出力場所へアトミックに移動することによって、各出力ファイル
が
1
つだけ存在することを自動的に保証してくれます。
10.7
トーングの
UI
Spark Streaming
は、アプリケーションが行っている処理の内容を見ることができ
る、特別な
UI
ページを提供しています。このページには、普通の
Spark
の
UI
（通常は
http://<driver>:4040
）の
Streaming
のタブからアクセスできます。サンプルのスクリーンショッ
トを
10-9
に示します。 ...
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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.