Connect to USPS as an External Data Source using PolyBase

Use the CData ODBC Driver for USPS and PolyBase to create an external data source in SQL Server 2019 with access to live USPS 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 USPS, you get access to your USPS data directly alongside your SQL Server data. This article walks through creating an external data source and external tables to grant access to live USPS data using T-SQL queries.

The CData ODBC drivers offer unmatched performance for interacting with live USPS data using PolyBase due to optimized data processing built into the driver. When you issue complex SQL queries from SQL Server to USPS, the driver pushes down supported SQL operations, like filters and aggregations, directly to USPS 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 USPS data, using a single query to pull data from distributed sources.

Connect to USPS

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 USPS Sys is created automatically).

To authenticate with USPS, set the following connection properties.

  • PostageProvider: The postage provider to use to process requests. Available options are ENDICIA and STAMPS. If unspecified, this property will default to ENDICIA.
  • UseSandbox: This controls whether live or test requests are sent to the production or sandbox servers. If set to true, the Password, AccountNumber, and StampsUserId properties are ignored.
  • StampsUserId: This value is used for logging into authentication to the Stamps servers. This value is not applicable for Endicia and is optional if UseSandbox is true.
  • Password: This value is used for logging into Endicia and Stamps servers. If the postage provider is Endicia, this will be the pass phrase associated with your postage account. It is optional if UseSandbox is true.
  • AccountNumber: The shipper's account number. It is optional if UseSandbox is true.
  • PrintLabelLocation: This property is required to use the GenerateLabels or GenerateReturnLabels stored procedures. This should be set to the folder location where generated labels should be stored.

The Cache Database

Many of the useful task available from USPS require a lot of data. To ensure this data is easy to input and recall later, utilize a cache database to make requests. Set the cache connection properties in order to use the cache:

  • CacheLocation: The path to the cache location, for which a connection will be configured with the default cache provider. For example, C:\users\username\documents\uspscache

As an alternative to CacheLocation, set the combination of CacheConnection and CacheProvider to configure a cache connection using a provider separate from the default.

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

Create an External Data Source for USPS 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 USPS data.

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

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

Create an External Data Source for USPS

Execute the following SQL command to create an external data source for USPS with PolyBase, using the DSN and credentials configured earlier.

For USPS, set SERVERNAME to 'localhost' or '127.0.0.1' and 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_usps_source
WITH ( 
  LOCATION = 'odbc://SERVERNAME[:PORT]',
  CONNECTION_OPTIONS = 'DSN=CData USPS Sys',
  -- PUSHDOWN = ON | OFF,
  CREDENTIAL = usps_creds
);

Create External Tables for USPS

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

CREATE EXTERNAL TABLE Senders(
  FirstName [nvarchar](255) NULL,
  Phone [nvarchar](255) NULL,
  ...
) WITH ( 
  LOCATION='Senders',
  DATA_SOURCE=cdata_usps_source
);

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