Book Image

Learning Cloudera Impala

By : Avkash Chauhan
Book Image

Learning Cloudera Impala

By: Avkash Chauhan

Overview of this book

<p>If you have always wanted to crunch billions of rows of raw data on Hadoop in a couple of seconds, then Cloudera Impala is the number one choice for you. Cloudera Impala provides fast, interactive SQL queries directly on your Apache Hadoop data stored in HDFS or HBase. In addition to using the same unified storage platform, Impala also uses the same metadata, SQL syntax (Hive SQL), ODBC driver, and user interface (Hue Beeswax) as Apache Hive. This provides a familiar and unified platform for batch-oriented or real-time queries.</p> <p>In this practical, example-oriented book, you will learn everything you need to know about Cloudera Impala so that you can get started on your very own project. The book covers everything about Cloudera Impala from installation, administration, and query processing, all the way to connectivity with other third party applications. With this book in your hand, you will find yourself empowered to play with your data in Hadoop.</p> <p>As a reader of this book, you will learn about the origin of Impala and the technology behind it that allows it to run on thousands of machines. You will learn how to install, run, manage, and troubleshoot Impala in your own Hadoop cluster using the step-by-step guidance provided in the book. The book covers tenets of data processing such as loading data stored in Hadoop into Impala tables and querying data using Impala SQL statements, all with various code illustrations and a real-world example.</p> <p>The book is written to get you started with Impala by providing rich information so you can understand what Impala is, what it can do for you, and finally how you can use it to achieve your objective.</p>
Table of Contents (15 chapters)
Learning Cloudera Impala
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

Connecting impala-shell to the remotely located impalad daemon


In some cases, impala-shell is installed manually on other machines that are not managed through Cloudera Manager. In such cases, you can still launch impala-shell and submit queries from those external machines to a DataNode where impalad is running. In such a specific scenario, impala-shell is started and connected to remote hosts by passing an appropriate hostname and port (if not the default, 21000).

To use Impala shell to connect to Impala daemons running on other DataNode machines, you just need to have a DataNode hostname and a port number where impalad is configured, to receive queries and pass both hostname and port with the connect <hostname:port> command, as shown in the following code:

[Not connected] > connect datanode-hostname  
[datanode-hostname:21000] >

As you can see, I did not include a port number with the connect command, and the connection to Impala daemon was made onto the default port 21000. If...