How to connect PolyBase to FHIR

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 FHIR, you get access to your FHIR data directly alongside your SQL Server data. This article describes creating an external data source and external tables to grant access to live FHIR 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 FHIR data using PolyBase due to optimized data processing built into the driver. When you issue complex SQL queries from SQL Server to FHIR, the driver pushes down supported SQL operations, like filters and aggregations, directly to FHIR 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 FHIR data, using a single query to pull data from distributed sources.

Connect to FHIR

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 FHIR Sys is created automatically).

Set URL to the Service Base URL of the FHIR server. This is the address where the resources are defined in the FHIR server you would like to connect to. Set ConnectionType to a supported connection type. Set ContentType to the format of your documents. Set AuthScheme based on the authentication requirements for your FHIR server.

Generic, Azure-based, AWS-based, and Google-based FHIR server implementations are supported.

Sample Service Base URLs

• Generic: http://my_fhir_server/r4b/
• Azure: https://MY_AZURE_FHIR.azurehealthcareapis.com/
• AWS: https://healthlake.REGION.amazonaws.com/datastore/DATASTORE_ID/r4/
• Google: https://healthcare.googleapis.com/v1/projects/PROJECT_ID/locations/LOCATION/datasets/DATASET_ID/fhirStores/FHIR_STORE_ID/fhir/

Generic FHIR Instances

The product supports connections to custom instances of FHIR. Authentication to custom FHIR servers is handled via OAuth (read more about OAuth in the Help documentation. Before you can connect to custom FHIR instances, you must set ConnectionType to Generic.

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

Create an External Data Source for FHIR 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 FHIR data.

NOTE: Since FHIR does not require a User or Password to authenticate, you may use whatever values you wish for IDENTITY and SECRET.

CREATE DATABASE SCOPED CREDENTIAL fhir_creds
WITH IDENTITY = 'username', SECRET = 'password';

Create an External Data Source for FHIR

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

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

For FHIR, 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_fhir_source
WITH ( 
  LOCATION = 'odbc://SERVER_URL',
  CONNECTION_OPTIONS = 'DSN=CData FHIR Sys',
  -- PUSHDOWN = ON | OFF,
  CREDENTIAL = fhir_creds
);

Create External Tables for FHIR

After creating the external data source, use CREATE EXTERNAL TABLE statements to link to FHIR data from your SQL Server instance. The table column definitions must match those exposed by the CData ODBC Driver for FHIR. 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 FHIR Patient would look similar to the following:

CREATE EXTERNAL TABLE Patient(
  Id [nvarchar](255) NULL,
  [name-use] [nvarchar](255) NULL,
  ...
) WITH ( 
  LOCATION='Patient',
  DATA_SOURCE=cdata_fhir_source
);

Having created external tables for FHIR 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 FHIR, freeing up local resources and computing power. Download a free, 30-day trial of the ODBC Driver for FHIR and start working with live FHIR data alongside your SQL Server data today.