January 2019
Beginner to intermediate
154 pages
4h 31m
English
Content preview from Apache Spark Quick Start Guide
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Action
You would have noticed that in every example we used, the collect() method to get the output. To get the final result back to the driver, Spark provides another type of operation known as actions. At the time of transformations, Spark chains these operations and constructs a DAG, but nothing gets executed. Once an action is performed on an RDD, it forces the evaluation of all the transformations required to compute that RDD.
Actions do not create a new RDD. They are used for the following:
- Returning final results to the driver
- Writing final result to an external storage
- Performing some operation on each element of that RDD (for example, foreach())
Let's discuss some of the basic actions.
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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.