Hive User Defined Aggregate Functions (UDAF) Java Example
Apache Hive is a data warehouse infrastructure built on top of Hadoop for providing data summarization, query, and analysis. Hive gives an SQL-like interface to query data stored in various databases and file systems that integrate with Hadoop. The traditional SQL queries must be implemented in the MapReduce Java API to execute SQL applications and queries over a distributed data. Hive provides the necessary SQL abstraction to integrate SQL-like Queries (HiveQL) into the underlying Java API without the need to implement queries in the low-level Java API. Since most of the data warehousing application work with SQL based querying language, Hive supports easy portability of SQL-based application to Hadoop.
1) A machine with Ubuntu 14.04 LTS operating system
2) Apache Hadoop 2.6.4 pre installed (How to install Hadoop on Ubuntu 14.04)
3) Apache Hive 2.1.0 pre installed (How to Install Hive on Ubuntu 14.04)
User Defined Aggregate Functions (UDAF) Java Example
Step 1 - Add these jar files to your java project.
Step 2 - Compile and create a jar file of your java project. Creating a jar file is left to you.
Step 3 - Create a Numbers_List.txt file
Step 4 - Add these following lines to Numbers_List.txt file
Step 5 - Change the directory to /usr/local/hive/bin
Step 6 - Enter into hive shell
Step 7 - Create a table Num_list, load Numbers_List.txt data into the table and verify. Save and close.
Step 8 - Add jar file in distributed cache, create a function and execute udaf function.
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