Temporary tables in AX 2012

In Ax 2012 we have 3 different types of tables. One type of temporary table is a TempDB table. We call them TempDB tables because their TableType property value is TempDB. This value comes from the TableType::TempDB enum value. The TableType property value can be set at AOT > Data Dictionary > Tables >MyTempDBTable > Properties > TableType.
Regular - a standard physical table
InMemory - the type of temporary table which existed in the previous versions of Dynamics Ax. Such tables are held in memory and written to a local disk file once they grow beyond a certain point
TempDB - a new option in Ax 2012. They are "physical" temporary tables held in the SQL Server database.

The new TempDB tables operate in a similar manner to InMemory tables but support more features of standard physical tables:
More powerful joins with physical tables are possible, and are properly supported by the database
Can be per-company or global
Support for normal tts transactions

To create a new instance link (populating data/copying reference) from one table instance variable to the other with Temporary type tables:
For InMemory tables, by using the setTmpData() method
For TempDB tables, the linkPhysicalTableInstance() method
replaces the setTmpData() call.

For more details on TempDB capabilities, Limitations, How to use, Its lifetime please check here - http://msdn.microsoft.com/en-us/library/gg845661.aspx