September 2012
Intermediate to advanced
350 pages
9h 46m
English
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Chapter 22. HCatalog
—Alan Gates
Introduction
Using Hive for data processing on Hadoop has several nice features beyond the ability to use an SQL-like language. It’s ability to store metadata means that users do not need to remember the schema of the data. It also means they do not need to know where the data is stored, or what format it is stored in. This decouples data producers, data consumers, and data administrators. Data producers can add a new column to the data without breaking their consumers’ data-reading applications. Administrators can relocate data to change the format it is stored in without requiring changes on the part of the producers or consumers.
The majority of heavy Hadoop users do not use a single tool for data production and consumption. Often, users will begin with a single tool: Hive, Pig, MapReduce, or another tool. As their use of Hadoop deepens they will discover that the tool they chose is not optimal for the new tasks they are taking on. Users who start with analytics queries with Hive discover they would like to use Pig for ETL processing or constructing their data models. Users who start with Pig discover they would like to use Hive for analytics type queries.
While tools such as Pig and MapReduce do not require metadata, they can benefit from it when it is present. Sharing a metadata store also enables users across tools to share data more easily. A workflow where data is loaded and normalized using MapReduce or Pig and then analyzed via Hive is very ...
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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.