How to connect PolyBase to CouchDB



Use CData drivers and PolyBase to create an external data source in SQL Server 2019 with access to live CouchDB data.

PolyBase for SQL Server allows you to query external data by using the same Transact-SQL syntax used to query a database table. When paired with the CData ODBC Driver for CouchDB, you get access to your CouchDB data directly alongside your SQL Server data. This article describes creating an external data source and external tables to grant access to live CouchDB data using T-SQL queries.

NOTE: PolyBase is only available on SQL Server 19 and above, and only for Standard SQL Server.

The CData ODBC drivers offer unmatched performance for interacting with live CouchDB data using PolyBase due to optimized data processing built into the driver. When you issue complex SQL queries from SQL Server to CouchDB, the driver pushes down supported SQL operations, like filters and aggregations, directly to CouchDB and utilizes the embedded SQL engine to process unsupported operations (often SQL functions and JOIN operations) client-side. And with PolyBase, you can also join SQL Server data with CouchDB data, using a single query to pull data from distributed sources.

Connect to CouchDB

If you have not already, first specify connection properties in an ODBC DSN (data source name). This is the last step of the driver installation. You can use the Microsoft ODBC Data Source Administrator to create and configure ODBC DSNs. To create an external data source in SQL Server using PolyBase, configure a System DSN (CData CouchDB Sys is created automatically).

Set the following to connect:

  • Url: The Url of your instance. For example: http://localhost:5984
  • User The Apache CouchDB user account used to authenticate.
  • Password The Apache CouchDB password associated with the authenticating user.

Click "Test Connection" to ensure that the DSN is connected to CouchDB properly. Navigate to the Tables tab to review the table definitions for CouchDB.

Create an External Data Source for CouchDB Data

After configuring the connection, you need to create a master encryption key and a credential database for the external data source.

Creating a Master Encryption Key

Execute the following SQL command to create a new master key, 'ENCRYPTION,' to encrypt the credentials for the external data source.

CREATE MASTER KEY ENCRYPTION BY PASSWORD = 'password';

Creating a Credential Database

Execute the following SQL command to create credentials for the external data source connected to CouchDB data.

NOTE: IDENTITY and SECRET correspond with the User and Password properties for CouchDB.


CREATE DATABASE SCOPED CREDENTIAL apachecouchdb_creds
WITH IDENTITY = 'apachecouchdb_username', SECRET = 'apachecouchdb_password';

Create an External Data Source for CouchDB

Execute a CREATE EXTERNAL DATA SOURCE SQL command to create an external data source for CouchDB with PolyBase:

  • Set the LOCATION parameter , using the DSN and credentials configured earlier.

For CouchDB, set SERVERNAME to the URL or address for your server (e.g. 'localhost' or '127.0.0.1' for local servers; the remote URL for remote servers). Leave PORT empty. PUSHDOWN is set to ON by default, meaning the ODBC Driver can leverage server-side processing for complex queries.


CREATE EXTERNAL DATA SOURCE cdata_apachecouchdb_source
WITH ( 
  LOCATION = 'odbc://SERVER_URL',
  CONNECTION_OPTIONS = 'DSN=CData CouchDB Sys',
  -- PUSHDOWN = ON | OFF,
  CREDENTIAL = apachecouchdb_creds
);

Create External Tables for CouchDB

After creating the external data source, use CREATE EXTERNAL TABLE statements to link to CouchDB data from your SQL Server instance. The table column definitions must match those exposed by the CData ODBC Driver for CouchDB. You can refer to the Tables tab of the DSN Configuration Wizard to see the table definition.

Sample CREATE TABLE Statement

The statement to create an external table based on a CouchDB Movies would look similar to the following:

CREATE EXTERNAL TABLE Movies(
  MovieRuntime [nvarchar](255) NULL,
  MovieRating [nvarchar](255) NULL,
  ...
) WITH ( 
  LOCATION='Movies',
  DATA_SOURCE=cdata_apachecouchdb_source
);

Having created external tables for CouchDB in your SQL Server instance, you are now able to query local and remote data simultaneously. Thanks to built-in query processing in the CData ODBC Driver, you know that as much query processing as possible is being pushed to CouchDB, freeing up local resources and computing power. Download a free, 30-day trial of the ODBC Driver for CouchDB and start working with live CouchDB data alongside your SQL Server data today.

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Learn more:

CouchDB Icon CouchDB ODBC Driver

The CouchDB ODBC Driver is a powerful tool that allows you to connect with live data from CouchDB, directly from any applications that support ODBC connectivity.

Access CouchDB data like you would a database - read, write, and update CouchDB. through a standard ODBC Driver interface.