Please find below
In our company we don't do that due to performance issues, it is better to save data in reporting database and make use of the same
The best way to connect Tableau to ServiceNow is to connect it to a mirrored database. It is not a good idea to connect live to ServiceNow because some complex queries might severely impair performance of the instance. The original ODBC driver is very limited as well.
We are very successful running Tableau against our own database with data downloaded via SnowMirror tool (www.snow-mirror.com). It's easy to use and you have your data in a real database such as Oracle or SQL Server.
Please read this post Connecting Tableau with Service Now
Thanks for the response. I heard that v10.3 had tableau servicenow ITSM connector, but we are still on v10.2 waiting for the upgrade.
To Vijaya's point about data warehousing, Explore Analytics allows you to run live or trended reports against ServiceNow data without having to copy data out and warehouse. That way you can just navigate through the SN Data Heirarchy as though you're reporting in ServiceNow, but with a lot more powerful visualizations, and able to connect to other data sources and combine them together.
One option is to use OpsHub Integration Manager ( http://www.opshub.com/products/opshub-integration-manager/ ) to enable one way integration / synchronization between the ServiceNow and a SQL Database (OpsHub supports Oracle, MySql and Microsoft Sql Server) to create the warehouse of all the information in ServiceNow. The warehouse can be set up to also contain all the changelog/ transition information.
OpsHub Integration Manager (OIM) is Now certified (certified by ServiceNow) and is available in ServiceNow store ( https://store.servicenow.com/sn_appstore_store.do#!/store/application/8e6f0b610f8ce6001f6fc3ace1050ebb ).
If you would like to further discussion on how to approach this problem or would like to get more information about OpsHub Integration Manager, Please reach out to us ( http://www.opshub.com/contactus/ ) and we will be happy to help with planning the solution.