Connect to Harvest Data as an External Data Source using PolyBase

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 Harvest, you get access to your Harvest data directly alongside your SQL Server data. This article describes creating an external data source and external tables to grant access to live Harvest data using T-SQL queries.

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

CData Connect AI provides a pure SQL Server interface for Harvest, allowing you to query data from Harvest without replicating the data to a natively supported database. Using optimized data processing out of the box, CData Connect AI pushes all supported SQL operations (filters, JOINs, etc.) directly to Harvest, leveraging server-side processing to return the requested Harvest data quickly.

Configure Harvest Connectivity for PolyBase

Connectivity to Harvest from PolyBase is made possible through CData Connect AI. To work with Harvest data from PolyBase, we start by creating and configuring a Harvest connection.

1. Log into Connect AI, click Sources, and then click Add Connection

2. Select "Harvest" from the Add Connection panel

3. Enter the necessary authentication properties to connect to Harvest.

   Start by setting the Profile connection property to the location of the Harvest Profile on disk (e.g. C:\profiles\Harvest.apip). Next, set the ProfileSettings connection property to the connection string for Harvest (see below).

   Harvest API Profile Settings

   To authenticate to Harvest, you can use either Token authentication or the OAuth standard. Use Basic authentication to connect to your own data. Use OAuth to allow other users to connect to their data.

   Using Token Authentication

   To use Token Authentication, set the APIKey to your Harvest Personal Access Token in the ProfileSettings connection property. In addition to APIKey, set your AccountId in ProfileSettings to connect.

   Using OAuth Authentication

   First, register an OAuth2 application with Harvest. The application can be created from the "Developers" section of Harvest ID.

   After setting the following connection properties, you are ready to connect:

   • ProfileSettings: Set your AccountId in ProfileSettings.
   • AuthScheme: Set this to OAuth.
   • OAuthClientId: Set this to the client ID that you specified in your app settings.
   • OAuthClientSecret: Set this to the client secret that you specified in your app settings.
   • CallbackURL: Set this to the Redirect URI that you specified in your app settings.
   • InitiateOAuth: Set this to GETANDREFRESH. You can use InitiateOAuth to manage how the driver obtains and refreshes the OAuthAccessToken.
   
4. Click Save & Test
5. Navigate to the Permissions tab in the Add Harvest Connection page and update the User-based permissions.

Add a Personal Access Token

When connecting to Connect AI through the REST API, the OData API, or the Virtual SQL Server, a Personal Access Token (PAT) is used to authenticate the connection to Connect AI. It is best practice to create a separate PAT for each service to maintain granularity of access.

1. Click on the Gear icon () at the top right of the Connect AI app to open the settings page.
2. On the Settings page, go to the Personal Access Tokens section and click Create PAT.
3. Give the PAT a name and click Create.
4. The personal access token is only visible at creation, so be sure to copy it and store it securely for future use.

With the connection configured and a PAT generated, you are ready to connect to Harvest data from Polybase.

Create an External Data Source for Harvest Data

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

Creating a Credential Database

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

NOTE: Set IDENTITY to your Connect AI username and set SECRET to your Personal Access Token.

CREATE DATABASE SCOPED CREDENTIAL ConnectAICredentials
WITH IDENTITY = 'yourusername', SECRET = 'yourPAT';

Create an External Data Source for Harvest

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

CREATE EXTERNAL DATA SOURCE ConnectAIInstance
WITH ( 
  LOCATION = 'sqlserver://tds.cdata.com:14333',
  PUSHDOWN = ON,
  CREDENTIAL = ConnectAICredentials
);

Create External Tables for Harvest

After creating the external data source, use CREATE EXTERNAL TABLE statements to link to Harvest data from your SQL Server instance. The table column definitions must match those exposed by CData Connect AI. You can use the Data Explorer in Connect AI to see the table definition.

Sample CREATE TABLE Statement

Execute a CREATE EXTERNAL TABLE SQL command to create the external table(s), using the collation and setting the LOCATION to three-part notation for the connection, catalog, and table. The statement to create an external table based on a Harvest Invoices would look similar to the following.

CREATE EXTERNAL TABLE Invoices(
  Id COLLATE [nvarchar](255) NULL,
  ClientName COLLATE [nvarchar](255) NULL,
  ...
) WITH ( 
  LOCATION='API1.API.Invoices',
  DATA_SOURCE=ConnectAIInstance
);

Having created external tables for Harvest in your SQL Server instance, you are now able to query local and remote data simultaneously. To get live data access to hundreds of SaaS, Big Data, and NoSQL sources directly from your SQL Server database, try CData Connect AI today!