HCatalog Altering Table
Apache HCatalog is a table management layer that exposes Hive metadata to other Hadoop applications. HCatalog's table abstraction presents users with a relational view of data in the Hadoop Distributed File System (HDFS) and ensures that users need not worry about where or in what format their data is stored. HCatalog displays data from RCFile format, text files, or sequence files in a tabular view. It also provides REST APIs so that external systems can access these table's metadata.
HCatalog is built on top of the Hive metastore and incorporates components from the Hive DDL. HCatalog provides read and write interfaces for Pig and MapReduce and uses Hive's command line interface for issuing data definition and metadata exploration commands. It also presents a REST interface to allow external tools access to Hive DDL (Data Definition Language) operations, such as "create table" and "describe table".
1) A machine with Ubuntu 14.04 LTS operating system installed.
2) Apache Hive 2.1.0 Pre Installed (How to Install Hive on Ubuntu 14.04)
3) Apache HCatalog merged with Hive (in March of 2013) HCatalog is now released as part of Hive. Here we are using latest version of HCatalog merged with Hive. (How to Install Hcatalog on Ubuntu 14.04)
HCatalog Alter Table
This post descibes, how to alter the attributes of a table such as changing its table name, changing column names, adding columns, and deleting or replacing columns.
Step 1 - Open a new terminal (CTRL + ALT + T) and Change the directory to /usr/local/hive/hcatalog/bin
Step 2 - Creating a new employee table
Step 3 - Check whether it is created or not. It shows all the tables that are present.
Step 4 - Altering Table
Alter table name
Change column name and type
Replace column name
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Labels : HCatalog Installation on Ubuntu HCatalog Command Line Interface (CLI) Usage HCatalog Creating Table HCatalog Script HCatalog Load Operation HCatalog Drop Table HCatalog Creating View and Index