Cloudera Engineering Blog · How-to Posts
Did you know that using the Crunch API is a powerful option for doing time-series analysis?
Apache Crunch is a Java library for building data pipelines on top of Apache Hadoop. (The Crunch project was originally founded by Cloudera data scientist Josh Wills.) Developers can spend more time focused on their use case by using the Crunch API to handle common tasks such as joining data sets and chaining jobs together in a pipeline. At Cloudera, we are so enthusiastic about Crunch that we have included it in CDH 5! (You can get started with Apache Crunch here and here.)
The internals of Oozie’s ShareLib have changed recently (reflected in CDH 5.0.0). Here’s what you need to know.
In a previous blog post about one year ago, I explained how to use the Apache Oozie ShareLib in CDH 4. Since that time, things have changed about the ShareLib in CDH 5 (particularly directory structure), so some of the previous information is now obsolete. (These changes went upstream under OOZIE-1619.)
Getting started with Spark (now shipping inside CDH 5) is easy using this simple example.
(Editor’s note – this post has been updated to reflect CDH 5.1/Spark 1.0)
Improved scheduling capabilities via Oozie in CDH 5 makes for far fewer headaches.
One of the best new Apache Oozie features in CDH 5, Cloudera’s software distribution, is the ability to use
cron-like syntax for coordinator frequencies. Previously, the frequencies had to be at fixed intervals (every hour or every two days, for example) – making scheduling anything more complicated (such as every hour from 9am to 5pm on weekdays or the second-to-last day of every month) complex and difficult.
The conclusion to this series covers how to use scans, and considerations for choosing the Thrift or REST APIs.
In this series of how-tos, you have learned how to use Apache HBase’s Thrift interface. Part 1 covered the basics of the API, working with Thrift, and some boilerplate code for connecting to Thrift. Part 2 showed how to insert and to get multiple rows at a time. In this third and final post, you will learn how to use scans and some considerations when choosing between REST and Thrift.
Scanning with Thrift
The CDH software stack lets you use your tool of choice with the Parquet file format – - offering the benefits of columnar storage at each phase of data processing.
An open source project co-founded by Twitter and Cloudera, Parquet was designed from the ground up as a state-of-the-art, general-purpose, columnar file format for the Apache Hadoop ecosystem. In particular, Parquet has several features that make it highly suited to use with Cloudera Impala for data warehouse-style operations:
This quick demo illustrates how easy it is to implement role-based access and control in Impala using Sentry.
Apache Sentry (incubating) is the Apache Hadoop ecosystem tool for role-based access control (RBAC). In this how-to, I will demonstrate how to implement Sentry for RBAC in Impala. I feel this introduction is best motivated by a use case.
Integrating Hue with LDAP can help make your secure Hadoop apps as widely consumed as possible.
Hue, the open source Web UI that makes Apache Hadoop easier to use, easily integrates with your corporation’s existing identity management systems and provides authentication mechanisms for SSO providers. So, by changing a few configuration parameters, your employees can start analyzing Big Data in their own browsers under an existing security policy.
Cloudera provides docs and a sample build environment to help you get easily started writing your own Impala UDFs.
User-defined functions (UDFs) let you code your own application logic for processing column values during a Cloudera Impala query. For example, a UDF could perform calculations using an external math library, combine several column values into one, do geospatial calculations, or other kinds of tests and transformations that are outside the scope of the built-in SQL operators and functions.
Developers, rejoice: Impala is now available on EMR for testing and evaluation.
Very recently, Amazon Web Services announced support for running Cloudera Impala queries on its Elastic MapReduce (EMR) service. This is very good news for EMR users — as well as for users of other platforms interested in kicking Impala’s tires in a friction-free way. It’s also yet another sign that Impala is rapidly being adopted across the ecosystem as the gold standard for interactive SQL and BI queries on Apache Hadoop.