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Hive – Create Database Examples

Prabha
hive create database

Using CREATE DATABASE statement you can create a new Database in Hive, like any other RDBMS Databases, the Hive database is a namespace to store the tables.

In this article, I will explain how to create a database, its syntax, and usage with examples in hive shell, Java and Scala languages.

Hive by default contains a default database, you can get this using SHOW DATABASES; statement.

Note: when you running SQL statements on Hive or beeline shell terminal, the statement should end with a semicolon.

Hive create database

Hive Create Database Syntax

In Hive, CREATE DATABASE statement is used to create a Database, this takes an optional clause IF NOT EXISTS, using this option, it creates only when database not already exists. 


CREATE DATABASE [IF NOT EXISTS] <database_name>

Note: Creating a database with already existing name in a database returns an error.

Create Database from Hive Beeline shell


jdbc:hive2://> CREATE DATABASE emp;
OK
Time taken: 0.929 seconds
jdbc:hive2://>

Make sure the database you are creating doesn’t exist on Hive warehouse, if exists it throws Database emp already exists error.


jdbc:hive2://> CREATE DATABASE emp;
FAILED: Execution Error, return code 1 from org.apache.hadoop.hive.ql.exec.DDLTask. Database emp already exists

If you wanted to check if the database already exists before creating, use IF NOT EXISTS clause.


jdbc:hive2://> CREATE DATABASE IF NOT EXISTS emp;
OK
Time taken: 0.063 seconds
jdbc:hive2://>

Hive by default creates a directory with a database name .db extension (for example emp.db) under its warehouse directory. By default warehouse directory located is /user/hive/warehouse on hdfs.


prabha@prabha:~$ hdfs dfs -ls /user/hive/warehouse
Found 1 items
drwxr-xr-x   - prabha supergroup          0 2020-10-03 21:30 /user/hive/warehouse/emp.db

You can change the location of the database where to create by using any of the below commands


jdbc:hive2://>CREATE DATABASE temp LOCATION '/apps/project/hive/warehouse';

You can also change the default location using hive.metastore.warehouse.dir


jdbc:hive2://>set hive.metastore.warehouse.dir='/apps/project/hive/warehouse';
jdbc:hive2://>CREATE DATABASE temp;

Show Database

In order to show the existing databases on Hive, use the SHOW DATABASES command.


jdbc:hive2://>> SHOW DATABASES;
OK
default
emp
Time taken: 0.059 seconds, Fetched: 2 row(s)

Creating a Database from Java & Scala

Let’s see how to create a Database from Java & Scala program, In order to connect and run Hive SQL you need to have hive-jdbc dependency and Hive JDBC connection string. You can download dependency from Maven or use the below dependency on your pom.xml.


<dependency>
    <groupId>org.apache.hive</groupId>
    <artifactId>hive-jdbc</artifactId>
    <version>3.1.2</version>
</dependency>

Below are complete Java and Scala examples of how to create a Database.

Note: If you are using an older version of Hive, you should use the driver org.apache.hadoop.hive.jdbc.HiveDriver and your connection string should be jdbc:hive://

In the below Java and Scala examples, I am connecting to the Hive default database and creating a new Hive database emp.

Java Example


package com.sparkbyexamples.hive;

import java.sql.Connection;
import java.sql.Statement;
import java.sql.DriverManager;

public class HiveCreateDatabase {
	public static void main(String[] args) {
		Connection con = null;
		try {
			String conStr = "jdbc:hive2://192.168.1.148:10000/default";
			Class.forName("org.apache.hive.jdbc.HiveDriver");
			con = DriverManager.getConnection(conStr, "", "");
			Statement stmt = con.createStatement();
			stmt.executeQuery("CREATE DATABASE emp");
			System.out.println("Database emp created successfully.");
		} catch (Exception ex) {
			ex.printStackTrace();
		} finally {
			try {
				if (con != null)
					con.close();
			} catch (Exception ex) {
			}
		}
	}
}

Scala Example


package com.sparkbyexamples.hive;

import java.sql.Connection;
import java.sql.Statement;
import java.sql.DriverManager;

object HiveCreateDatabase extends App{
	var con = null;
	try {
		val conStr = "jdbc:hive2://192.168.1.148:10000/default";
		Class.forName("org.apache.hive.jdbc.HiveDriver");
		con = DriverManager.getConnection(conStr, "", "");
		val stmt = con.createStatement();
		stmt.executeQuery("CREATE DATABASE emp");
		System.out.println("Database emp created successfully.");
	} catch (Exception ex) {
		ex.printStackTrace();
	} finally {
		try {
			if (con != null)
				con.close();
		} catch (Exception ex) {
		}
	}
}

Conclusion

In this article, you have learned creating a Database using hive shell, java, Scala program and also learned it by default stores a database at /user/hive/warehouse directory path and finally learned how to change the default location path.

Happy Learning !!

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