How Random Sampling in Hive Works, And How to Use It

Random sampling is a technique in which each sample has an equal probability of being chosen. A sample chosen randomly is meant to be an unbiased representation of the total population.

In the big data world, we have an enormous total population: a population that can prove tricky to truly sample randomly. Thankfully, Hive has a few tools for realizing the dream of random sampling in the data lake. Continue reading

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How to Build Optimal Hive Tables Using ORC, Partitions and Metastore Statistics

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Creating Hive tables is a common experience to all of us that use Hadoop. It enables us to mix and merge datasets into unique, customized tables. And, there are many ways to do it.

We have some recommended tips for Hive table creation that can increase your query speeds and optimize and reduce the storage space of your tables. And it’s simpler than you might think. Continue reading

How to Write ORC Files and Hive Partitions in Spark

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ORC, or Optimized Row Columnar, is a popular big data file storage format. Its rise in popularity is due to it being highly performant, very compressible, and progressively more supported by top-level Apache products, like Hive, Crunch, Cascading, Spark, and more.

I recently wanted/needed to write ORC files from my Spark pipelines, and found specific documentation lacking. So, here’s a way to do it. Continue reading

How to Build Data History in Hadoop with Hive: Part 2

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Part 2: Growing the data

If you’ve yet to finish part one, we strongly encourage reading it. It’s not super long.

It’s time to get technical. Continue reading

How to Build Data History in Hadoop with Hive: Part 1

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The Wind Up

One of the key benefits of Hadoop is its capacity for storing large quantities of data. With HDFS (the Hadoop Distributed File System), Hadoop clusters are capable of reliably storing petabytes of your data.

A popular usage of that immense storage capability is storing and building history for your datasets. You can not only utilize it to store years of data you might currently be deleting, but you can also build on that history! And, you can structure the data within a Hadoop-native tool like Hive and give analysts SQL-querying ability to that mountain of data! And it’s pretty cheap!

…And the Pitch!

In this tutorial, we’ll walk through why this is beneficial, and how we can implement it on a technical level in Hadoop. Something for the business guy, something for the developer tasked with making the dream come true.

The point of Hadoopsters is to teach concepts related to big data, Hadoop, and analytics. To some, this article will be too simple — low hanging fruit for the accomplished dev. This article is not necessarily for you, captain know-it-all — it’s for someone looking for a reasonably worded, thoughtfully explained how-to on building data history in native Hadoop. We hope to accomplish that here.

Let’s get going. Continue reading

How to Sqoop an RDBMS Source Directly to a Hive Table In Any Format

This tutorial will accomplish a few key feats that make ingesting data to Hive far less painless. In this writeup, you will learn not only how to Sqoop a source table directly to a Hive table, but also how to Sqoop a source table in any desired format (ORC, for example) instead of just plain old text.

Continue reading

Create a Hive UDF: More Flexible Array Access

 

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This article will show you how to create a simple UDF that offers more flexibility in interacting with arrays in Hive, such as a negative indexing approach to element access. Continue reading

How to Create a Simple Hive UDF

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There are many functions in Hive that can help analyze your data. But there are times when you need more functionality, sometimes custom. Or at least functionality that is possible without paragraphs of ugly, layered-sub-queried SQL.

That’s where Hive UDFs come in very handy. Continue reading

Preparing for the HDPCD Exam: Data Analysis With Hive

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With your data now in HDFS in an “analytic-ready” format (it’s all cleaned and in common formats), you can now put a Hive table on top of it.

Apache Hive is a RDBMS-like layer for data in HDFS that allows you to run batch or ad-hoc queries in a SQL-like language. This post will go over what you need to know about Apache Hive in preparation for the HDPCD Exam.  Continue reading