Cloudera Developer Blog · Hive Posts

How-to: Use a SerDe in Apache Hive

Apache Hive is a fantastic tool for performing SQL-style queries across data that is often not appropriate for a relational database. For example, semistructured and unstructured data can be queried gracefully via Hive, due to two core features: The first is Hive’s support of complex data types, such as structs, arrays, and unions, in addition to many of the common data types found in most relational databases. The second feature is the SerDe.

What is a SerDe?

The SerDe interface allows you to instruct Hive as to how a record should be processed. A SerDe is a combination of a Serializer and a Deserializer (hence, Ser-De). The Deserializer interface takes a string or binary representation of a record, and translates it into a Java object that Hive can manipulate. The Serializer, however, will take a Java object that Hive has been working with, and turn it into something that Hive can write to HDFS or another supported system. Commonly, Deserializers are used at query time to execute SELECT statements, and Serializers are used when writing data, such as through an INSERT-SELECT statement.

Cloudera Speakers at ApacheCon NA 2013

Our hearty congratulations to the Cloudera engineers who have been accepted as ApacheCon NA 2013 (Feb. 26-28 in Portland, OR) speakers for these talks:

Secrets of Cloudera Support: The Champagne Strategy

At Cloudera, we put great pride into drinking our own champagne. That pride extends to our support team, in particular.

Cloudera Manager, our end-to-end management platform for CDH (Cloudera’s open-source, enterprise-ready distribution of Apache Hadoop and related projects), has a feature that allows subscription customers to send a snapshot of their cluster to us. When these cluster snapshots come to us from customers, they end up in a CDH cluster at Cloudera where various forms of data processing and aggregation can be performed. 

Analyzing Twitter Data with Apache Hadoop, Part 3: Querying Semi-structured Data with Apache Hive

This is the third article in a series about analyzing Twitter data using some of the components of the Apache Hadoop ecosystem that are available in CDH (Cloudera’s open-source distribution of Apache Hadoop and related projects). If you’re looking for an introduction to the application and a high-level view, check out the first article in the series.

In the previous article in this series, we saw how Flume can be utilized to ingest data into Hadoop. However, that data is useless without some way to analyze the data. Personally, I come from the relational world, and SQL is a language that I speak fluently. Apache Hive provides an interface that allows users to easily access data in Hadoop via SQL. Hive compiles SQL statements into MapReduce jobs, and then executes them across a Hadoop cluster.

The New "Hadoop in Practice" Book: A Chat with The Author

Today we bring you a brief interview with Alex Holmes, author of the new book, Hadoop in Practice (Manning). You can learn more about the book and download a free sample chapter here.

There are a few good Hadoop books on the market right now. Why did you decide to write this book, and how is it complementary to them?
When I started working with Hadoop I leaned heavily on Tom White’s excellent book, Hadoop: The Definitive Guide (O’Reilly Media), to learn about MapReduce and how the internals of Hadoop worked. As my experience grew and I started working with Hadoop in production environments I had to figure out how to solve problems such as moving data in and out of Hadoop, using compression without destroying data locality, performing advanced joining techniques and so on. These items didn’t have a lot of coverage in existing Hadoop books, and that’s really the idea behind Hadoop in Practice – it’s a collection of real-world recipes that I learned the hard way over the years.

Cloudera Impala: Real-Time Queries in Apache Hadoop, For Real

After a long period of intense engineering effort and user feedback, we are very pleased, and proud, to announce the Cloudera Impala project. This technology is a revolutionary one for Hadoop users, and we do not take that claim lightly.

When Google published its Dremel paper in 2010, we were as inspired as the rest of the community by the technical vision to bring real-time, ad hoc query capability to Apache Hadoop, complementing traditional MapReduce batch processing. Today, we are announcing a fully functional, open-sourced codebase that delivers on that vision – and, we believe, a bit more – which we call Cloudera Impala. An Impala binary is now available in public beta form, but if you would prefer to test-drive Impala via a pre-baked VM, we have one of those for you, too. (Links to all downloads and documentation are here.) You can also review the source code and testing harness at Github right now.

CDH4.1 Now Released!

Update time!  As a reminder, Cloudera releases major versions of CDH, our 100% open source distribution of Apache Hadoop and related projects, annually and then updates to CDH every three months.  Updates primarily comprise bug fixes but we will also add enhancements.  We only include fixes or enhancements in updates that maintain compatibility, improve system stability and still allow customers and users to skip updates as they see fit.

We’re pleased to announce the availability of CDH4.1.  We’ve seen excellent adoption of CDH4.0 since it went GA at the end of June and a number of exciting use cases have moved to production.  CDH4.1 is an update that has a number of fixes but also a number of useful enhancements.  Among them:

How-to: Analyze Twitter Data with Apache Hadoop

Social media has gained immense popularity with marketing teams, and Twitter is an effective tool for a company to get people excited about its products. Twitter makes it easy to engage users and communicate directly with them, and in turn, users can provide word-of-mouth marketing for companies by discussing the products. Given limited resources, and knowing we may not be able to talk to everyone we want to target directly, marketing departments can be more efficient by being selective about whom we reach out to.

In this post, we’ll learn how we can use Apache Flume, Apache HDFS, Apache Oozie, and Apache Hive to design an end-to-end data pipeline that will enable us to analyze Twitter data. This will be the first post in a series. The posts to follow to will describe, in more depth, how each component is involved and how the custom code operates. All the code and instructions necessary to reproduce this pipeline is available on the Cloudera Github.

Who is Influential?

Community Meetups at Strata + Hadoop World 2012

Strata Conference + Hadoop World (Oct. 23-25 in New York City) is a bonanza for Hadoop and big data enthusiasts – but not only because of the technical sessions and tutorials. It’s also an important gathering place for the developer community, most of whom are eager to share info from their experiences in the “trenches”.

Just to make that process easier, Cloudera is teaming up with local meetups during that week to organize a series of meetings on a variety of topics. (If for no other reason, stop into one of these meetups for a chance to grab a coveted Cloudera t-shirt.)

What Do Real-Life Apache Hadoop Workloads Look Like?

Organizations in diverse industries have adopted Apache Hadoop-based systems for large-scale data processing. As a leading force in Hadoop development with customers in half of the Fortune 50 companies, Cloudera is in a unique position to characterize and compare real-life Hadoop workloads. Such insights are essential as developers, data scientists, and decision makers reflect on current use cases to anticipate technology trends.

Recently we collaborated with researchers at UC Berkeley to collect and analyze a set of Hadoop traces. These traces come from Cloudera customers in e-commerce, telecommunications, media, and retail (Table 1). Here I will explain a subset of the observations, and the thoughts they triggered about challenges and opportunities in the Hadoop ecosystem, both present and in the future.

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