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Connect to Impala Data as a Federated Tables in MySQL

Use the CData Cloud Hub to set up federated tables for Impala data in MySQL .

You can use the CData Cloud Hub to set up federated tables in MySQL for Impala data. The Cloud Hub provides a MySQL interface for Impala: After configuring a virtual MySQL database for Impala, you can create a server and tables using the FEDERATED Storage Engine in MySQL. You can then work with Impala data just as you would local MySQL tables.

The CData Cloud Hub provides a pure MySQL, cloud-to-cloud interface for Impala, allowing you to easily query live Impala data alongside existing MySQL data — all without replicating the data. Using optimized data processing out of the box, the CData Cloud Hub pushes all supported SQL operations (filters, JOINs, etc) directly to Impala, leveraging server-side processing to quickly return Impala data.

Create a Virtual MySQL Database for Impala Data

CData Cloud Hub uses a straightforward, point-and-click interface to connect to data sources and generate APIs.

  1. Login to Cloud Hub and click Databases.
  2. Select "Impala" from Available Data Sources.
  3. Enter the necessary authentication properties to connect to Impala.

    In order to connect to Apache Impala, set the Server, Port, and ProtocolVersion. You may optionally specify a default Database. To connect using alternative methods, such as NOSASL, LDAP, or Kerberos, refer to the online Help documentation.

  4. Click Test Database.
  5. Click Privileges -> Add and add the new user (or an existing user) with the appropriate permissions.

With the virtual database created, you are ready to connect to Impala data from any MySQL client.

Create a FEDERATED Server and Tables for Impala Data

After you have configured and started the service, create a FEDERATED server to simplify the process of creating FEDERATED tables:

Create a FEDERATED Server

The following statement will create a FEDERATED server based on the Cloud Hub. Note that the username and password of the FEDERATED server must match a user account you defined on the Cloud Hub.

CREATE SERVER fedApacheImpala
FOREIGN DATA WRAPPER mysql
OPTIONS (USER 'cloud_hub_user', PASSWORD 'cloud_hub_passwd', HOST 'myinstance.cdatacloud.net', PORT 3306, DATABASE 'impaladb');

Create a FEDERATED Table

To create a FEDERATED table using our newly created server, use the CONNECTION keyword and pass the name of the FEDERATED server and the remote table (Customers). Refer to the following template for the statement to create a FEDERATED table:

CREATE TABLE fed_customers (
  ...,
  city  TYPE(LEN),
  companyname  TYPE(LEN),
  ...,
)
ENGINE=FEDERATED
DEFAULT CHARSET=utf8
CONNECTION='fedApacheImpala/Customers';

NOTE: The table schema for the FEDERATED table must match the remote table schema exactly. You can always connect directly to the Cloud Hub using any MySQL client and run SHOW COLUMNS FROM Customers to get the table schema.

Execute Queries

You can now execute queries to the Impala FEDERATED tables from any tool that can connect to MySQL, which is particularly useful if you need to JOIN data from a local table with data from Impala. Refer to the following example:

SELECT 
  fed_customers.city, 
  local_table.custom_field 
FROM 
  local_table 
JOIN 
  fed_customers 
ON 
  local_table.foreign_city = fed_customers.city;