Creating custom User-Defined Functions (UDF)
Built-in functions in Hive sometimes do not fit the requirements of a business use case or when data analytics required some custom manipulation of data based on certain conditions. For such cases, the user needs to define custom logic as a UDF and run it over the data.
How to do it…
For writing a custom function in Hive, you will have to extend a Hive class: org.apache.hadoop.hive.ql.exec.UDF.
Let's understand the concept of creating a custom UDF with the example of creating a function to reverse a string.
The following are the steps to create a custom UDF:
- Create a new Java project using any IDE, such as Eclipse. Give this any name; let's say "
HiveUDF". - When writing a custom UDF, there should be two libraries ...
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