Connect to SQL Analysis Services 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 SQL Analysis Services, you get access to your SQL Analysis Services data directly alongside your SQL Server data. This article describes creating an external data source and external tables to grant access to live SQL Analysis Services 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 SQL Analysis Services, allowing you to query data from SQL Analysis Services 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 SQL Analysis Services, leveraging server-side processing to return the requested SQL Analysis Services data quickly.

Configure SQL Analysis Services Connectivity for PolyBase

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

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

2. Select "SQL Analysis Services" from the Add Connection panel

3. Enter the necessary authentication properties to connect to SQL Analysis Services.

   To connect, provide authentication and set the Url property to a valid SQL Server Analysis Services endpoint. You can connect to SQL Server Analysis Services instances hosted over HTTP with XMLA access. See the Microsoft documentation to configure HTTP access to SQL Server Analysis Services.

   To secure connections and authenticate, set the corresponding connection properties, below. The data provider supports the major authentication schemes, including HTTP and Windows, as well as SSL/TLS.

   • HTTP Authentication

     Set AuthScheme to "Basic" or "Digest" and set User and Password. Specify other authentication values in CustomHeaders.

   • Windows (NTLM)

     Set the Windows User and Password and set AuthScheme to "NTLM".

   • Kerberos and Kerberos Delegation

     To authenticate with Kerberos, set AuthScheme to NEGOTIATE. To use Kerberos delegation, set AuthScheme to KERBEROSDELEGATION. If needed, provide the User, Password, and KerberosSPN. By default, the data provider attempts to communicate with the SPN at the specified Url.

   • SSL/TLS:

     By default, the data provider attempts to negotiate SSL/TLS by checking the server's certificate against the system's trusted certificate store. To specify another certificate, see the SSLServerCert property for the available formats.

   You can then access any cube as a relational table: When you connect the data provider retrieves SSAS metadata and dynamically updates the table schemas. Instead of retrieving metadata every connection, you can set the CacheLocation property to automatically cache to a simple file-based store.

   See the Getting Started section of the CData documentation, under Retrieving Analysis Services Data, to execute SQL-92 queries to the cubes.

   
4. Click Save & Test
5. Navigate to the Permissions tab in the Add SQL Analysis Services 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 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 SQL Analysis Services data from Polybase.

Create an External Data Source for SQL Analysis Services 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 SQL Analysis Services data.

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

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

Create an External Data Source for SQL Analysis Services

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

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

Create External Tables for SQL Analysis Services

After creating the external data source, use CREATE EXTERNAL TABLE statements to link to SQL Analysis Services 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 SQL Analysis Services Adventure_Works would look similar to the following.

CREATE EXTERNAL TABLE Adventure_Works(
  Fiscal_Year COLLATE [nvarchar](255) NULL,
  Sales_Amount COLLATE [nvarchar](255) NULL,
  ...
) WITH ( 
  LOCATION='SSAS1.SSAS.Adventure_Works',
  DATA_SOURCE=ConnectCloudInstance
);

Having created external tables for SQL Analysis Services 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!