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.
167
9
Spark SQL
本章では、構造化データや半構造化データを扱うための
Spark
のインターフェイスである、
Spark SQL
を紹介します。構造化データとは、ーを持っているデータのことです。スキー
マとは、各レコードのための既知のフィールドの集合です。この種のデータを持っているなら、
Spark SQL
を使うことで、ロードもクエリも容易かつ効率的になります。具体的には、
Spark
SQL
が提供する主要な機能は次の
3
つです。
1.
さまざまな構造化ソースからのデータのロード（
JSON
、
Hive
、
Parquet
など）。
2. SQL
を使ったデータのクエリ。クエリは、
Spark
のプログラム内からでも、
Tableau
な
どのビジネスインテリジェンスツールなど、外部のツールから標準的なデータベース接続
（
JDBC/ODBC
）を通じて
Spark SQL
に接続しても実行できる。
3. Spark
のプログラム内から使われる場合、
Spark SQL
は
SQL
と標準的な
Python/Java/
Scala
のコードとの多彩な結合方法を提供する。その中には、
RDD
と
SQL
のテーブルと
の結合、
SQL
でのカスタム関数の利用などが含まれる。この組み合わせを利用すること
で、多くのジョブが書きやすくなる。
これらの機能を実装するために、
Spark SQL
は
SchemaRDD
と呼ばれる特別な種類の
RDD
を
提供します
†
。
SchemaRDD
は
Row
オブジェクトからなる
RDD
で、それぞれの
Row
オブジェクト
がレコードを表現します。 ...
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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.