- Impala Tutorial
- Impala - Home
- Impala - Overview
- Impala - Environment
- Impala - Architecture
- Impala - Shell
- Impala - Query Language Basics
- Database Specific Statements
- Impala - Create a Database
- Impala - Drop a Database
- Impala - Select a Database
- Table Specific Statements
- Impala - Create Table Statement
- Impala - Insert Statement
- Impala - Select Statement
- Impala - Describe Statement
- Impala - Alter Table
- Impala - Drop a Table
- Impala - Truncate a Table
- Impala - Show Tables
- Impala - Create View
- Impala - Alter View
- Impala - Drop a View
- Impala - Clauses
- Impala - Order By Clause
- Impala - Group By Clause
- Impala - Having Clause
- Impala - Limit Clause
- Impala - Offset Clause
- Impala - Union Clause
- Impala - With Clause
- Impala - Distinct Operator
- Impala Useful Resources
- Impala - Quick Guide
- Impala - Useful Resources
- Impala - Discussion
Impala - Create a Database
In Impala, a database is a construct which holds related tables, views, and functions within their namespaces. It is represented as a directory tree in HDFS; it contains tables partitions, and data files. This chapter explains how to create a database in Impala.
CREATE DATABASE Statement
The CREATE DATABASE Statement is used to create a new database in Impala.
Syntax
Following is the syntax of the CREATE DATABASE Statement.
CREATE DATABASE IF NOT EXISTS database_name;
Here, IF NOT EXISTS is an optional clause. If we use this clause, a database with the given name is created, only if there is no existing database with the same name.
Example
Following is an example of the create database statement. In this example, we have created a database with the name my_database.
[quickstart.cloudera:21000] > CREATE DATABASE IF NOT EXISTS my_database;
On executing the above query in cloudera impala-shell, you will get the following output.
Query: create DATABASE my_database Fetched 0 row(s) in 0.21s
Verification
The SHOW DATABASES query gives the list of the databases in Impala, therefore you can verify whether the database is created, using the SHOW DATABASES statement. Here you can observe the newly created database my_db in the list.
[quickstart.cloudera:21000] > show databases; Query: show databases +-----------------------------------------------+ | name | +-----------------------------------------------+ | _impala_builtins | | default | | my_db | +-----------------------------------------------+ Fetched 3 row(s) in 0.20s [quickstart.cloudera:21000] >
Hdfs Path
In order to create a database in HDFS file system, you need to specify the location where the database is to be created.
CREATE DATABASE IF NOT EXISTS database_name LOCATION hdfs_path;
Creating a Database using Hue Browser
Open Impala Query editor and type the CREATE DATABASE statement in it. Thereafter, click the execute button as shown in the following screenshot.
After executing the query, gently move the curser to the top of the dropdown menu and you will find a refresh symbol. If you click on the refresh symbol, the list of databases will be refreshed and the recent changes are applied to it.
Verification
Click the drop-down box under the heading DATABASE on the left-hand side of the editor. There you can see a list of databases in the system. Here you can observe the newly created database my_db as shown below.
If you observe carefully, you can see only one database, i.e., my_db in the list along with the default database.
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