Google BigQuery Connector - Using T-SQL / Linked Server

T-SQL is a programming language used for managing and querying data in Microsoft SQL Server databases. We provides tools for data integration, automation, and connectivity.

If you want to use T-SQL with ZappySys, you can use our Connector, which allows you to connect to SQL Server databases and execute T-SQL queries from Google BigQuery.

Create Data Source in ZappySys Data Gateway based on ZappySys API Driver

Download and install ZappySys ODBC PowerPack.
Search for gateway in start menu and Open ZappySys Data Gateway:
Go to Users Tab to add our first Gateway user. Click Add; we will give it a name tdsuser and enter password you like to give. Check Admin option and click OK to save. We will use these details later when we create linked server:
Now we are ready to add a data source. Click Add, give data source a name (Copy this name somewhere, we will need it later) and then select Native - ZappySys API Driver. Finally, click OK. And it will create the Data Set for it and open the ZS driver UI.

GoogleBigQueryDSN
When the Configuration window appears give your data source a name if you haven't done that already, then select "Google BigQuery" from the list of Popular Connectors. If "Google BigQuery" is not present in the list, then click "Search Online" and download it. Then set the path to the location where you downloaded it. Finally, click Continue >> to proceed with configuring the DSN:

GoogleBigQueryDSN

Google BigQuery

Now it's time to configure the Connection Manager. Select Authentication Type, e.g. Token Authentication. Then select API Base URL (in most cases, the default one is the right one). More info is available in the Authentication section.

User Account [OAuth]

Steps to get Google BigQuery Credentials
This connection can be configured using two ways. Use Default App (Created by ZappySys) OR Use Custom App created by you.
To use minimum settings you can start with ZappySys created App. Just change UseCustomApp=false on the properties grid so you dont need ClientID / Secret. When you click Generate Token you might see warning about App is not trusted (Simply Click Advanced Link to expand hidden section and then click Go to App link to Proceed).

To register custom App, perform the following steps (Detailed steps found in the help link at the end)

Go to Google API Console
From the Project Dropdown (usually found at the top bar) click Select Project
On Project Propup click CREATE PROJECT
Once project is created you can click Select Project to switch the context (You can click on Notification link or Choose from Top Dropdown)
Click ENABLE APIS AND SERVICES
Now we need to Enable two APIs one by one (BigQuery API and Cloud Resource Manager API).
Search BigQuery API. Select and click ENABLE
Search Cloud Resource Manager API. Select and click ENABLE
Go to back to main screen of Google API Console
Click OAuth consent screen Tab. Enter necessary details and Save.
1. Choose Testing as Publishing status
2. Set application User type to Internal, if possible
3. If MAKE INTERNAL option is disabled, then add a user in Test users section, which you will use in authentication process when generating Access and Refresh tokens
Click Credentials Tab
Click CREATE CREDENTIALS (some where in topbar) and select OAuth Client ID option.
When prompted Select Application Type as Desktop App and click Create to receive your ClientID and Secret. You can use this information now to configure Connection with UseCustomApp=true.

Fill in all required parameters and set optional parameters if needed:

GoogleBigQueryDSN

Google BigQuery

User Account [OAuth]

https://www.googleapis.com/bigquery/v2

Required Parameters
UseCustomApp	Fill in the parameter...
ProjectId (Choose after [Generate Token] clicked)	Fill in the parameter...
DatasetId (Choose after [Generate Token] clicked and ProjectId selected)	Fill in the parameter...
Optional Parameters
ClientId	Fill in the parameter...
ClientSecret	Fill in the parameter...
Scope	Fill in the parameter...
RetryMode	Fill in the parameter...
RetryStatusCodeList	Fill in the parameter...
RetryCountMax	Fill in the parameter...
RetryMultiplyWaitTime	Fill in the parameter...
Job Location	Fill in the parameter...

Service Account (Using Private Key File) [OAuth]

Steps to get Google BigQuery Credentials
Use these steps to authenticate as service account rather than Google / GSuite User. Learn more about service account here

Basically to call Google API as Service account we need to perform following steps listed in 3 sections (Detailed steps found in the help link at the end)

Create Project

First thing is create a Project so we can call Google API. Skip this section if you already have Project (Go to next section)

Go to Google API Console
From the Project Dropdown (usually found at the top bar) click Select Project
On Project Propup click CREATE PROJECT
Once project is created you can click Select Project to switch the context (You can click on Notification link or Choose from Top Dropdown)
Click ENABLE APIS AND SERVICES
Now we need to Enable two APIs one by one (BigQuery API and Cloud Resource Manager API).
Search BigQuery API. Select and click ENABLE
Search Cloud Resource Manager API. Select and click ENABLE

Create Service Account

Once Project is created and APIs are enabled we can now create a service account under that project. Service account has its ID which looks like some email ID (not to confuse with Google /Gmail email ID)

Go to Create Service Account
From the Project Dropdown (usually found at the top bar) click Select Project
Enter Service account name and Service account description
Click on Create. Now you should see an option to assign Service Account permissions (See Next Section).

Give Permission to Service Account

By default service account cant access BigQuery data or List BigQuery Projects so we need to give that permission using below steps.

After you Create Service Account look for Permission drop down in the Wizard.
Choose BigQuery -> BigQuery Admin role so we can read/write data. (NOTE: If you just need read only access then you can choose BigQuery Data Viewer)
Now choose one more Project -> Viewer and add that role so we can query Project Ids.
Click on Continue. Now you should see an option to Create Key (See Next Section).

Create Key (P12)

Once service account is created and Permission is assigned we need to create key file.

In the Cloud Console, click the email address for the service account that you created.
Click Keys.
Click Add key, then click Create new key.
Click Create and select P12 format. A P12 key file is downloaded to your computer. We will use this file in our API connection.
Click Close.
Now you may use downloaded *.p12 key file as secret file and Service Account Email as Client ID (e.g. some_name@some_name.iam.gserviceaccount.com).

Manage Permissions / Give Access to Other Projects

We saw how to add permissions for Service Account during Account Creation Wizard but if you ever wish to edit after its created or you wish to give permission for other projects then perform forllowing steps.

From the top Select Project for which you like to edit Permission.
Go to IAM Menu option (here)
Link to IAM: https://console.cloud.google.com/iam-admin/iam
Goto Permissions tab. Over there you will find ADD button.
Enter Service account email for which you like to grant permission. Select role you wish to assign.

Fill in all required parameters and set optional parameters if needed:

GoogleBigQueryDSN

Google BigQuery

Service Account (Using Private Key File) [OAuth]

https://www.googleapis.com/bigquery/v2

Required Parameters
Service Account Email	Fill in the parameter...
Service Account Private Key Path (i.e. *.p12)	Fill in the parameter...
ProjectId	Fill in the parameter...
DatasetId (Choose after ProjectId)	Fill in the parameter...
Optional Parameters
Scope	Fill in the parameter...
RetryMode	Fill in the parameter...
RetryStatusCodeList	Fill in the parameter...
RetryCountMax	Fill in the parameter...
RetryMultiplyWaitTime	Fill in the parameter...
Job Location	Fill in the parameter...

Once the data source has been configured, you can preview data. Select the Preview tab and use settings similar to the following to preview data:
Click OK to finish creating the data source.

Read data in SQL Server from the ZappySys Data Gateway

To read the data in SQL Server the first thing you have to do is create a Linked Server. Go to SQL Server Management Studio and configure it in a similar way:
Then click on Security option and configure username we created in ZappySys Data Gateway in one of the previous steps:
Optional: Under the Server Options, Enable RPC and RPC Out and Disable Promotion of Distributed Transactions(MSDTC).

You need to enable RPC Out if you plan to use EXEC(...) AT [MY_LINKED_SERVER_NAME] rather than OPENQUERY.
If don't enabled it, you will encounter the Server 'MY_LINKED_SERVER_NAME' is not configured for RPC error.

Query Example:
```
EXEC('Select * from Products') AT [MY_LINKED_SERVER_NAME]
```
If you plan to use 'INSERT INTO...EXEC(....) AT [MY_LINKED_SERVER_NAME]' in that case you need to Disable Promotion of Distributed Transactions(MSDTC).
If don't disabled it, you will encounter the The operation could not be performed because OLE DB provider "SQLNCLI11" for linked server "MY_LINKED_SERVER_NAME" was unable to begin a distributed transaction. error.

Query Example:
```
Insert Into dbo.Products
 EXEC('Select * from Products') AT [MY_LINKED_SERVER_NAME]
```
Finally, open a new query and execute a query we saved in one of the previous steps:
```
SELECT * FROM OPENQUERY([MY_LINKED_SERVER_NAME], 'SELECT * FROM Products');
```

Create Linked Server using Code

In previous section you saw how to create a Linked Server from UI. You can do similar action by code too (see below). Run below script after changing necessary parameters. Assuming your Data Source name on ZappySys Data Gateway UI is 'GoogleBigQueryDSN'


    USE [master]
    GO
    --///////////////////////////////////////////////////////////////////////////////////////
    --Run below code in SSMS to create Linked Server and use ZappySys Drivers in SQL Server
    --///////////////////////////////////////////////////////////////////////////////////////

    //Replace YOUR_GATEWAY_USER, YOUR_GATEWAY_PASSWORD
    //Replace localhost with IP/Machine name if ZappySys Gateway Running on different machine other than SQL Server
    //Replace Port 5000 if you configured gateway on a different port


    --1. Configure your gateway service as per this article https://zappysys.com/links?id=10036
    
    --2. Make sure you have SQL Server Installed. You can download FREE SQL Server Express Edition from here if you dont want to buy Paid version https://www.microsoft.com/en-us/sql-server/sql-server-editions-express

    --Uncomment below if you like to drop linked server if it already exists
    --EXEC master.dbo.sp_dropserver @server=N'LS_GoogleBigQueryDSN', @droplogins='droplogins'

    --3. Create new linked server
    
    EXEC master.dbo.sp_addlinkedserver
      @server = N'LS_GoogleBigQueryDSN'  --Linked server name (this will be used in OPENQUERY sql
    , @srvproduct=N''
    , @provider=N'SQLNCLI11'
    , @datasrc=N'localhost,5000' --//Machine / Port where Gateway service is running
    , @provstr=N'Network Library=DBMSSOCN;'
    , @catalog=N'GoogleBigQueryDSN' --Data source name you gave on Gateway service settings

    --4. Attach gateway login with linked server

    EXEC master.dbo.sp_addlinkedsrvlogin
      @rmtsrvname=N'LS_GoogleBigQueryDSN'  --linked server name
    , @useself=N'False'
    , @locallogin=NULL
    , @rmtuser=N'YOUR_GATEWAY_USER' --enter your Gateway user name
    , @rmtpassword='YOUR_GATEWAY_PASSWORD'  --enter your Gateway user's password
    GO

    --5. Enable RPC OUT (This is Optional - Only needed if you plan to use EXEC(...) AT YourLinkedServerName rather than OPENQUERY
    EXEC sp_serveroption 'LS_GoogleBigQueryDSN', 'rpc', true;
    EXEC sp_serveroption 'LS_GoogleBigQueryDSN', 'rpc out', true;

    --Disable MSDTC - Below needed to support INSERT INTO from EXEC AT statement
    EXEC sp_serveroption 'LS_GoogleBigQueryDSN', 'remote proc transaction promotion', false;
    
    --Increase query timeout if query is going to take longer than 10 mins (Default timeout is 600 seconds)
    --EXEC sp_serveroption 'LS_GoogleBigQueryDSN', 'query timeout', 1200;
    GO