having 10s of thousands of books in my library, i find the built in calibre search ultra slow.
So I did something similar to this - built my own separate app to export the calibre metadata into elasticsearch so i could have faster searches and instantly find duplicates.... metadata import only takes seconds.
(it's actually a calibre importer app - i select a folder of books i want to import into calibre, and as i highlight a book from the filesystem to review and import, it finds whether or not that book is already in calibre)
but mine was a meta-data only solution - this goes beyond that, and is integrated into calibre itself
