How to upgrade SQL Server 2008 to 2012 with table partition?
If you're talking about partitioning that utilizes partition schemes and partition functions in Sql Server 2008, you're obviously using Enterprise Edition.  That functionality has been supported in all Enterprise releases since its inception in 2005.  

As of Sql server 2016 SP1, that functionality is supported in ALL editions.

Generally speaking, anytime you are preparing to upgrade from one version of Sql Server to another (2008 -> 2012, etc.), it's prudent to run the Upgrade Advisor tool for the release you are targeting.


  Upgrade Advisor analyzes installed components from earlier versions of
  SQL Server, and then generates a report that identifies issues to fix
  either before or after you upgrade.