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PolyBase で外部データソースとしてGmail を連携利用

CData ODBC Driver for Gmail とSQL Server 2019 のPolyBase を使って、リアルタイムGmail data に外部データソースとしてアクセス。

SQL Server のPolyBase は、データベーステーブルをクエリするTransact-SQL シンタックスを使って、外部データにクエリする仕組みです。 CData ODBC Drivers for Gmail data を組み合わせて使うことで、SQL Server データと同じようにGmail data へのアクセスが可能です。 本記事では、PolyBase 外部データソースへのGmail data の設定から、T-SQL クエリを使ったGmail data へのアクセスを行います。

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

Gmail への接続

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 Gmail Sys is created automatically).

There are two ways to authenticate to Gmail. Before selecting one, first ensure that you have enabled IMAP access in your Gmail account settings. See the "Connecting to Gmail" section under "Getting Started" in the installed documentation for a guide.

The User and Password properties, under the Authentication section, can be set to valid Gmail user credentials.

Alternatively, instead of providing the Password, you can use the OAuth authentication standard. To access Google APIs on behalf on individual users, you can use the embedded credentials or you can register your own OAuth app.

OAuth also enables you to use a service account to connect on behalf of users in a Google Apps domain. To authenticate with a service account, you will need to register an application to obtain the OAuth JWT values.

In addition to the OAuth values, you will need to provide the User. See the "Getting Started" chapter in the help documentation for a guide to using OAuth.

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

Gmail Data の外部データソースの作成

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 Gmail data.

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

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

Create an External Data Source for Gmail

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

For Gmail, 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_gmail_source
WITH ( 
  LOCATION = 'odbc://SERVERNAME[:PORT]',
  CONNECTION_OPTIONS = 'DSN=CData Gmail Sys',
  -- PUSHDOWN = ON | OFF,
  CREDENTIAL = gmail_creds
);

Gmail のExternal Table を作成

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

CREATE EXTERNAL TABLE Inbox(
  Subject [nvarchar](255) NULL,
  Size [nvarchar](255) NULL,
  ...
) WITH ( 
  LOCATION='Inbox',
  DATA_SOURCE=cdata_gmail_source
);

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

 
 
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