September 2012
Intermediate to advanced
350 pages
9h 46m
English
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Chapter 11. Other File Formats and Compression
One of Hive’s unique features is that Hive does not force data
to be converted to a specific format. Hive leverages Hadoop’s InputFormat APIs to read data from a variety of
sources, such as text files, sequence files, or even custom formats.
Likewise, the OutputFormat API is used to
write data to various formats.
While Hadoop offers linear scalability in file storage for uncompressed data, storing data in compressed form has many benefits. Compression typically saves significant disk storage; for example, text-based files may compress 40% or more. Compression also can increase throughput and performance. This may seem counterintuitive because compressing and decompressing data incurs extra CPU overhead, however, the I/O savings resulting from moving fewer bytes into memory can result in a net performance gain.
Hadoop jobs tend to be I/O bound, rather than CPU bound. If so, compression will improve performance. However, if your jobs are CPU bound, then compression will probably lower your performance. The only way to really know is to experiment with different options and measure the results.
Determining Installed Codecs
Based on your Hadoop version, different codecs will be
available to you. The set feature in
Hive can be used to display the value of hiveconf or Hadoop configuration values. The
codecs available are in a comma-separated list named io.compression.codec:
#hive-e"set io.compression.codecs"io.compression.codecs=org.apache ...
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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.