Expression Tag/Backfilling

I want to do metric with multiple tags and therefore I created expression tags. Works fine and writing to history works perfect too.

How can i calculate these metrics backwards and save them to the historian?

Expression tag configuration: {[~]machine1/energy_input}/{[~]machine1/production}

This gives me energy efficiency at the moment. By writing the result back to the historian I can always look at the trend. Both tags ({[~]machine1/energy_input},…) were stored into the historian for several years and the expression tag is new.

How can I tell ignition to calculate the expression tag for several years in the past?

Please give an example of your inputs and the outputs you want. It’s not clear from your question. (You can edit the original post with the pencil icon.)