...

SELECT ENo,EName,Sys_Start,Sys_End
FROM Emp FOR SYSTEM_TIME BETWEEN
 TIMESTAMP '2011-01-02 00:00:00'AND
 TIMESTAMP '2011-12-31 00:00:00' 

Rejected Alternatives

Add SupportsTimeTravel source ability

SupportTimeTravel Source Ability will be applied in the optimization phase, but Time Travel TimeTravel is not only an ability of Source, but also needs support from Catalog. Travel not only requires obtaining data at the corresponding time point, but also requires the corresponding Schema at that time point. Therefore, TimeTravel is not only an ability of Source, but also needs support from Catalog.    

As a Source ability, SupportTimeTravel will be applied during SQL optimization, which means that it can't meet the requirement for the TableSchema TimeTravel. 

Add SupportsTimeTravel source ability

Here is the brief implement plan. 

...