Please advise how to handle following scenario in web application.

I have a drop-down which is populated using meta-data from table A. When form is submitted this drop down data is stored in table B. While displaying existing data, it is populated using data stored in table B. While copying existing data, it is copied using data stored in table B.

I want to achieve following goals:

1. While displaying existing data I must display data irrespective of current meta data (to explain, even if some options are removed from metadata I still display them).

2. When I copy existing data only current data should be copied(that is if some options are removed from metadata I should not copy them).

I understand that I can do this by scanning metadata every time I copy existing data, however if there are thousands of such drop down exist, it is definitely not desirable to scan complete metadata for every drop down.

How can I handle such situation in web application?