Data Loading | Hive Tutorial Part-5 | How to Load Data? | Moving Data from HDFS
Course Materials
https://github.com/venkatareddykonasa...
To keep up with the latest updates, join our WhatsApp community: https://chat.whatsapp.com/GidY7xFaFtk...
In this Hive tutorial, we explore the process of loading data into tables step-by-step. We'll cover how to check for data on HDFS (Hadoop Distributed File System), create tables, and load data into them—all within the Hive environment.
Firstly, we verify if our data exists on HDFS. Since we moved our data previously during MapReduce and HDFS commands, we can check its presence using the HDFS command. In Hive, we can directly use ""DFS -ls"" to list the contents of HDFS.
Upon inspection, we find our Stack Overflow data, a 7GB text file, already residing on HDFS. This file was initially moved here as part of our data preparation.
Next, we proceed to load this data into the empty table we previously created. Our table, named ""stackoverflow_tags,"" currently has no data, but our Stack Overflow data on HDFS is ready to be moved into it.
The command to achieve this is straightforward: ""LOAD DATA INPATH 'stack_over_HDFS' INTO TABLE stackoverflow_tags."" Here, we specify the path to our HDFS data set and the target table.
After executing this command, we now have data loaded into our table. We can confirm this by running a simple count query: ""SELECT COUNT(*) FROM stackoverflow_tags."" This query initiates a MapReduce process behind the scenes to count the number of rows in our table.
As the MapReduce job progresses, we see the status updates—map 1%, map 5%, map 12%, and so on. Despite the large dataset, Hive efficiently handles the process, automatically generating the necessary Map and Reduce functions.
Finally, once the MapReduce job completes, we receive the result: our table contains approximately 6.34 million observations, mirroring the size of our data set. This entire process, which previously required a complex MapReduce program in Java, is now accomplished with a single SQL-like command in Hive.
Hive simplifies complex data operations, making it accessible to those without a MapReduce or coding background. Whether you're new to data processing or a seasoned analyst, this tutorial provides an easy-to-follow guide for loading data into Hive tables.
Don't forget to like, share, and subscribe for more Hive tutorials and data processing tips!
#HiveTutorial #DataLoading #HDFS #SQLCommands #dataprocessing #bigdata #hive