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.
186
9 章 Spark SQL
9.5.2
Hive
の
UDF
Spark SQL
では、
Hive
の既存の
UDF
を使うこともできます。標準的な
Hive
の
UDF
は、最初
から自動的にインクルードされます。カスタムの
UDF
がある場合は、その
UDF
の
JAR
群がアプ
リケーションに含まれているようにすることが重要です。
JDBC
サーバーを使う場合に注意しなけ
ればならないのは、
JAR
を
コマンドラインフラグの
--jars
で追加しなければならないことです。
Hive
の
UDF
の開発方法は本書の範疇を超えているので、ここでは既存の
Hive UDF
の使い方だ
けを紹介します。
Hive
の
UDF
を使うには、通常の
SQLContext
ではなく、
HiveContext
を使う必要があります。
Hive
の
UDF
は、
hiveCtx.sql("CREATE TEMPORARY FUNCTION name AS
class.function
")
とするだ
けで使えるようになります。
9.6
Spark SQL
のフーン
始めに触れた通り、
Spark SQL
は、高レベルのクエリ言語と型情報の追加によって、効率的に
動作できます。
Spark SQL
は、
SQL
に慣れているユーザーのためだけのものではありません。
Spark SQL
を使
えば、複数の列の合計値の計算（
9-40
のような条件付きの集計操作を、
6
で議論したよ
うな特別なオブジェクトを構築することなく簡単に行えるようになります。
9-40
Spark SQL
...
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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.