Apache Hive is a data warehouse framework on top of Hadoop ecosystem. The Apache Hive architecture is different compared to other Hadoop tools that are available. Being an open source project, Apache Hive has added a lot of functionalities since its inception. But it still lacks some basic functionalities that are available in traditional data warehouse systems such as Netezza, Teradata, Oracle, etc. In this post, we will check Apache Hive user-defined functions and how to use them to perform a specific task.
Apache Hive User-defined Functions
When you start using Apache Hive, you may miss some features that you used in traditional data warehouse systems. In Hive, user-defined functions are used to satisfy specific client needs. The best part about Hadoop is, it provides an API to use your favorite programming language. You can write user-defined functions in Java, Scala or Python.
Why Hive User-defined Functions?
As mentioned earlier, user-defined functions (UDFs) are used to perform a specific task or some of UDFs are specifically designed for the reusability of code in application frameworks. The developer can use any programming language that Hive supports to write Hive UDFs and integrate those functions with Hive queries.
Once you have function created and registered in Hive, you can directly use that function in your Hive queries and UDFs will return outputs according to the user defined tasks. It will provide high performance in terms of coding and execution.
Hive User-defined Function uses
You can write Hive reusable UDFs to perform specific tasks.
For example, Hive does not have rich built-in function to convert date values to the required formats. You can create Hive user-defined function to convert date value to a particular format.
The general type of UDF will accept a single input value and produce a single output value.
Apache Hive User-defined Function Example
Since the Hadoop framework is written in Java, most of the Hadoop developers prefer Java to write the Hive UDFs. However, you can Hadoop Streaming Interface to integrate UDFs written in other programming languages such as Python.
Here is an excellent post on creating UDFs using Python – Hive User-defined Function Example
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Hope this helps 🙂