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Connect to MongoDB Data as a Federated Tables in MySQL

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

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

The CData Cloud Hub provides a pure MySQL, cloud-to-cloud interface for MongoDB, allowing you to easily query live MongoDB 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 MongoDB, leveraging server-side processing to quickly return MongoDB data.

Create a Virtual MySQL Database for MongoDB 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 "MongoDB" from Available Data Sources.
  3. Enter the necessary authentication properties to connect to MongoDB.

    Set the Server, Database, User, and Password connection properties to connect to MongoDB. To access MongoDB collections as tables you can use automatic schema discovery or write your own schema definitions. Schemas are defined in .rsd files, which have a simple format. You can also execute free-form queries that are not tied to the schema.

  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 MongoDB data from any MySQL client.

Create a FEDERATED Server and Tables for MongoDB 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 fedMongoDB
FOREIGN DATA WRAPPER mysql
OPTIONS (USER 'cloud_hub_user', PASSWORD 'cloud_hub_passwd', HOST 'myinstance.cdatacloud.net', PORT 3306, DATABASE 'mongodbdb');

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 (restaurants). Refer to the following template for the statement to create a FEDERATED table:

CREATE TABLE fed_restaurants (
  ...,
  borough  TYPE(LEN),
  cuisine  TYPE(LEN),
  ...,
)
ENGINE=FEDERATED
DEFAULT CHARSET=utf8
CONNECTION='fedMongoDB/restaurants';

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 restaurants to get the table schema.

Execute Queries

You can now execute queries to the MongoDB 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 MongoDB. Refer to the following example:

SELECT 
  fed_restaurants.borough, 
  local_table.custom_field 
FROM 
  local_table 
JOIN 
  fed_restaurants 
ON 
  local_table.foreign_borough = fed_restaurants.borough;