This is the documentation for CDH 5.1.x. Documentation for other versions is available at Cloudera Documentation.

Databases

In Impala, a database is a logical container for a group of tables. Each database defines a separate namespace. Within a database, you can refer to the tables inside it using their unqualified names. Different databases can contain tables with identical names.

Creating a database is a lightweight operation. There are no database-specific properties to configure. Therefore, there is no ALTER DATABASE

Typically, you create a separate database for each project or application, to avoid naming conflicts between tables and to make clear which tables are related to each other.

Each database is physically represented by a directory in HDFS.

There is a special database, named default, where you begin when you connect to Impala. Tables created in default are physically located one level higher in HDFS than all the user-created databases.

Impala includes another predefined database, _impala_builtins, that serves as the location for the built-in functions. To see the built-in functions, use a statement like the following:

show functions in _impala_builtins;
show functions in _impala_builtins like '*substring*';

Related statements: CREATE DATABASE Statement, DROP DATABASE Statement, USE Statement

Page generated September 3, 2015.