Data Frame Partial Caching

Kevin Feasel

2016-07-11

Spark

Arijit Tarafdar shows how to capture partitions of a data frame in Spark, either horizontally or vertically:

In many Spark applications, performance benefit is obtained from caching the data if reused several times in the applications instead of reading them each time from persistent storage. However, there can be situations when the entire data cannot be cached in the cluster due to resource constraint in the cluster and/or the driver. In this blog we describe two schemes that can be used to partially cache the data by vertical and/or horizontal partitioning of the Distributed Data Frame (DDF) representing the data. Note that these schemes are application specific and are beneficial only if the cached part of the data is used multiple times in consecutive transformations or actions.

In the notebook we declare a Student case class with name, subject, major, school and year as members. The application is required to find out the number of students by name, subject, major, school and year.

Partitioning is an interesting idea for trying to speed up Spark performance by keeping everything in memory even when your entire data set is a bit too large.

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