A PostgreSQL Interface for Bitbucket Data using the CData ODBC Driver

There are a vast number of PostgreSQL clients available on the Internet. From standard Drivers to BI and Analytics tools, PostgreSQL is a popular interface for data access. Using the SQL Gateway included in our ODBC Drivers, you can now create PostgreSQL entry-points that you can connect to from any standard client.

To access Bitbucket data as a PostgreSQL database on Windows, use the CData SQL Gateway, the ODBC Driver for Bitbucket, and the MySQL foreign data wrapper from EnterpriseDB. In this article, we compile the foreign data wrapper in Visual Studio, install it as an extension, and query Bitbucket data from PostgreSQL Server.

Configure the Connection to Bitbucket

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.

For most queries, you must set the Workspace. The only exception to this is the Workspaces table, which does not require this property to be set, as querying it provides a list of workspace slugs that can be used to set Workspace. To query this table, you must set Schema to 'Information' and execute the query SELECT * FROM Workspaces>.

Setting Schema to 'Information' displays general information. To connect to Bitbucket, set these parameters:

• Schema: To show general information about a workspace, such as its users, repositories, and projects, set this to Information. Otherwise, set this to the schema of the repository or project you are querying. To get a full set of available schemas, query the sys_schemas table.
• Workspace: Required if you are not querying the Workspaces table. This property is not required for querying the Workspaces table, as that query only returns a list of workspace slugs that can be used to set Workspace.

Authenticating to Bitbucket

Bitbucket supports OAuth authentication only. To enable this authentication from all OAuth flows, you must create a custom OAuth application, and set AuthScheme to OAuth.

Be sure to review the Help documentation for the required connection properties for you specific authentication needs (desktop applications, web applications, and headless machines).

Creating a custom OAuth application

From your Bitbucket account:

1. Go to Settings (the gear icon) and select Workspace Settings.
2. In the Apps and Features section, select OAuth Consumers.
3. Click Add Consumer.
4. Enter a name and description for your custom application.
5. Set the callback URL:
   • For desktop applications and headless machines, use http://localhost:33333 or another port number of your choice. The URI you set here becomes the CallbackURL property.
   • For web applications, set the callback URL to a trusted redirect URL. This URL is the web location the user returns to with the token that verifies that your application has been granted access.
6. If you plan to use client credentials to authenticate, you must select This is a private consumer. In the driver, you must set AuthScheme to client.
7. Select which permissions to give your OAuth application. These determine what data you can read and write with it.
8. To save the new custom application, click Save.
9. After the application has been saved, you can select it to view its settings. The application's Key and Secret are displayed. Record these for future use. You will use the Key to set the OAuthClientId and the Secret to set the OAuthClientSecret.

Start the Remoting Service

The MySQL remoting service is a daemon process that listens for clients' incoming MySQL connections. See the setup guide in the SQL Gateway overview to configure the MySQL Remoting service in the CData SQL Gateway.

Build the MySQL Foreign Data Wrapper

The Foreign Data Wrapper can be installed as an extension to PostgreSQL, without recompiling PostgreSQL. If you are running PostgreSQL on a Unix-based system, you can use the PostgreSQL Extension Network (PGXN) to install the FDW, mysql_fdw. If you are running PostgreSQL on Windows, compile the extension to ensure that you are working with the latest version. Follow the steps below to make the necessary modifications to build the extension from Visual Studio:

Obtain Prerequisites

To build the foreign data wrapper, do the following:

• Install PostgreSQL. This example uses an installation of PostgreSQL 9.4.
• Obtain the source for the mysql_fdw foreign data wrapper from EnterpriseDB.
• Install MySQL Connector C. This example uses an installation of MySQL Connector C 6.1.

Configure a Project

After you have obtained the necessary software and source code, you are ready to compile the extension with Visual Studio. Follow the steps below to create a project using the mysql_fdw source:

1. In Visual Studio, create a new empty C++ project.
2. In Solution Explorer, right-click Source Files and click Add -> Existing Item. In the file explorer, select all of the .c and .h files from the mysql_fdw source.

Follow the steps below to configure your project:

1. If you are building for a 64-bit system, click Build -> Configuration Manager and in Active Solution Platform select x64.
2. Right-click your project and click Properties.
3. In the Configuration menu, select All Configurations.
4. In Configuration Properties -> General -> Configuration Type, select Dynamic Library.
5. In Configuration Properties -> C/C++ -> Code Generation -> Enable C++ Exceptions, select No.
6. In Configuration Properties -> C/C++ -> Advanced -> Compile As, select Compile as C Code.
7. In Linker -> Manifest File -> Generate Manifest, select No.

Follow the steps below to add the required dependencies:

1. In Linker -> Input -> Additional Dependencies, select Edit and enter the following:

   postgres.lib
   libmysql.lib
   WS2_32.lib
   Secur32.lib
   

   Additionally, ensure that Inherit From Parent or Project Defaults is checked.
2. In Linker -> General -> Additional Library Directories, select Edit and add
   • the path to the lib folder in your PostgreSQL installation
   • the path to the lib folder for your MySQL Connector C installation
3. In Linker -> General -> Link Library Dependencies, select No.
4. To complete the configuration of your project, add the necessary includes: In C/C++ -> General -> Additional Include Directories, add the following folders in the following order:

   MyMySQLConnectorCInstallation\include
   MyPostgreSQLInstallation\MyPostgreSQLVersion\include\server\port\win32_msvc
   MyPostgreSQLInstallation\MyPostgreSQLVersion\include\server\port\win32
   MyPostgreSQLInstallation\MyPostgreSQLVersion\include\server
   MyPostgreSQLInstallation\MyPostgreSQLVersion\include
   

Configure mysql_fdw for Windows

After setting up a project, make the following changes to build mysql_fdw in Visual Studio:

1. In mysql_fdw.c, add the following defines:

   #define dlsym(lib, name) (void*)GetProcAddress((HMODULE)lib, name)
   #define dlopen(libname, unused) LoadLibraryEx(libname, NULL, 0)
   

2. In the mysql_load_library definition, delete the following line:

   mysql_dll_handle = dlopen(_MYSQL_LIBNAME, RTLD_LAZY | RTLD_DEEPBIND);
   

3. Add the following line in the mysql_load_library definition to replace the assignment of mysql_dll_handle for a Windows build:

   mysql_dll_handle = dlopen("libmysql.dll", 0);
   

4. Prepend the call to the mysql_fdw_handler function with the __declspec(dllexport) keyword to export the function from the DLL:

   __declspec(dllexport) extern Datum mysql_fdw_handler(PG_FUNCTION_ARGS);

5. In option.c, prepend the declaration of the mysql_fdw_validator function with the __declspec(dllexport) keyword to export the function from the DLL:

   __declspec(dllexport) extern Datum mysql_fdw_validator(PG_FUNCTION_ARGS);

You can now select the Release configuration and build.

Install the Extension

After you have compiled the DLL, follow the steps below to install the extension:

1. Add the path to the lib folder for MySQL Connector C to the PATH environment variable of the machine running PostgreSQL.
2. Copy the DLL from the RElease folder for your project into the lib subfolder of your PostgreSQL installation.
3. In the folder containing the mysql_fdw csource files, copy myswl_fdw--1.0.sql and mysql_fdw.control into the extension folder under the share folder of your PostgreSQL installation. For example: C:\Program Files\PostgreSQL\9.4\share\extension.

Query Bitbucket Data as a PostgreSQL Database

After you have installed the extension, follow the steps below to start executing queries to Bitbucket data:

1. Log into your PostgreSQL database. For example:

   C:\> psql -U postgres
   

2. Load the extension for the database:

   postgres=#CREATE EXTENSION mysql_fdw;
   

3. Create a server object for Bitbucket data:

   postgres=# CREATE SERVER Bitbucket FOREIGN DATA WRAPPER mysql_fdw OPTIONS (host
   '127.0.0.1', port '3306');
   

4. Create a user mapping for the username and password of a user known to the MySQL remoting service. Below are the credentials for the user in the sample configuration of the service:

   postgres=# CREATE USER MAPPING for postgres SERVER Bitbucket OPTIONS (username
   'admin', password 'test');
   

5. Create the local schema:

   postgres=# CREATE SCHEMA Bitbucket_db;

6. Import all the tables in the Bitbucket database you defined:

   postgres=# IMPORT FOREIGN SCHEMA "CData Bitbucket Sys" FROM SERVER Bitbucket INTO Bitbucket_db;
   

You can now execute read/write commands to Bitbucket:

postgres=# SELECT * FROM Bitbucket_db."issues";