Quick Question about book covers

Is there a way to make the book covers be included in the .db file?

I would like to get rid of a buttload of redundant book files, but still want the "library" for metadata mining. Having the covers makes a huge difference.

I know that if I just remove the books from the files (I have the ability to "flat view" all my folders) it would leave the covers, but I recall at one time or another being able to create an exact duplicate of a library from the json and db files - to the point that the library indicated the book format in the details.