Note: Currently only the Windows version of Tableau Desktop support ODBC connections. Tableau Public and all OS X version do not support ODBC connection.
To configure a connection to a MonetDB database, download and install Tableau, followed by the ODBC driver (download here). Be careful to download the appropriate version (32 or 64-bit) based on your system - 64-bit Tableau will only work with a 64-bit ODBC driver on a 64-bit Windows.
Next, (after having started the your database instance and loaded your data), open Tableau to configure the connection. From the welcome screen select Connect to data, scroll to the bottom of the On a server list and select Other Databases (ODBC). After that fill in the required details for connection to the MonetDB server:
1) Select DSN and find MonetDB from the drop down menu
2) Click connect to initialize the driver. If no system-wide DSN has been configured, you can now enter the details for database connection.
3) Type in the hostname of the server - localhost in our case.
4) Type in the port of the database server - 50000 by default.
5) Enter the database name - demo is the default database on Windows MonetDB installations.
6) Type in the username and password for the database.
Click OK and Tableau will establish a connection with the database instance.
Next, to get ready for data exploration or reporting you need to select which tables should be loaded in a Tableau worksheet.
1) Open the Schema drop down menu, click on the search button to list all schemas and select that one with your data tables - sys by default.
2) Open the Table drop down menu and click on the search button to list all to list all schemas. Selecting more than one table will usually bring up a menu to join the rows in a single query. Alternatively you can write you own Custom SQL query.
3) Select the table(s) you want to be added for visualisation. Depending on the data size, you might want to enable Automatically Update the table contents.
4) Click on the Go to Worksheet button.
That's it, you can now explore and visualise the data with Tableau.
You can also find more about Tableau and ODBC connection on their website.