August 2015
Intermediate to advanced
312 pages
7h 28m
Japanese
Content preview from 初めてのSpark
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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.
111
6.4 パーティション単位での処理
めの時間が急速にボトルネックになっていくためです。特に、
Spark
の
Scala
や
Java
の
API
でデ
フォルトのシリアライゼーションライブラリとして使用されている
Java Serialization
は、配列や
プリミティブ型以外を扱う場合、そのままでは非常に効率が悪くなることがあります。シリアラ
イゼーションを最適化するには、
spark.serializer
プロパティを使って別のシリアライゼーショ
ンライブラリを選択したり（
8
では、高速なシリアライゼーションライブラリである
Kyro
の使
用方法を説明します）、あるいは独自のデータ型に対する独自のシリアライゼーションルーチンを
実装する（例えば、
Java Serialization
の
java.io.Externalizable
インターフェイスを使ったり、
reduce()
メソッドを使って
Python
の
pickle
ライブラリ用のカスタムシリアライゼーションを定
義したりすることができます）という方法があります。
6.4
ーテンの理
データをパーティション単位で処理することで、データアイテムごとにセットアップの処理を繰
り返さずに済むようになります。要素ごとに行いたくはないセットアップのステップの例として
は、データベースへの接続や乱数ジェネレータの生成があります。
Spark
にはー
バージョンの
map
および
foreach
があり、
RDD
の各パーティションごとに
1
度だけ
コードが実行されるようにすることで、こうした処理のコストを削減しやすくしてくれます。 ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access
More than 5,000 organizations count on O’Reilly
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.