Question about metadata in epub files vs opf files

[machstem]

I had a hard time recovering from a screw-up recently; I used calibre-web to access the metadata.db file while my calibre client also had access, AND accidentally used lazylibrarian which then tried to manipulate the database and corrupted it.

Fast forward 3 days and now I have 3 calibre libraries; one for my client that I connect to my kobo device, one for the calibre-web service which is basically created/updated by an rsync from my master calibre library, and another completely separated one for cleaning up new books, etc.

My questions is this:

If I manage an epub file and I have adjusted some of the metadata such as the id links for goodreads/amazon, comment/description or even the book cover, do my epub files get converted with these newer metadata values?

For example, I downloaded a couple of common-creative epub files with some rather plain cover art, and an underwhelming comment. I then used calibre to download the metadata for that book, made it look nice and ready to send to my kobo.

What exactly is being sent to my kobo using the calibre program? Is it only the original .EPUB file that I imported, or is it the .EPUB file adjusted to fit all the newer changes I made to them? If I were to use my Windows Explorer to copy over the same .EPUB file referenced in calibre, are the same files sent over with the same metadata?

I hope this makes sense.

Thanks!

[kovidgoyal]

calibre does not update metadata in book copies in its library. metadata is stored in its own internal database. Whenever you export a book from calibre, the metadata is updated in that exported copy at export time.

[machstem]

Originally Posted by kovidgoyal

calibre does not update metadata in book copies in its library. metadata is stored in its own internal database. Whenever you export a book from calibre, the metadata is updated in that exported copy at export time.

Exactly what I hoped to hear.

So, now that my newest calibre library is slowly being cleaned up, and my existing books will have the newest covers/descriptions, could I now convert them to another .EPUB file with all the newest metadata? (in case of a future database corruption)

Then I can either remove and backup the original .EPUB file and use the newest ones.

Thanks again for the prompt answer; I can't believe how efficient you've been with this software of yours. You are one heck of a dedicated developer.

[kovidgoyal]

Yes a conversion updates metadata in the converted copy, or you can use the dedicated embed metadata tool (prefrences->toolbars and add it to your main toolbar).