Comment 2 for bug 1593027

Thanks for the tips and the rapid response. I'll test both approaches.

On Wed, Jun 15, 2016 at 9:58 PM, Kovid Goyal <email address hidden>
wrote:

> Copying to library has to first serialize metadata, then import it into
> the destination library. Importing directly makes use of the already
> serialized metadata in the OPF file -- so it will always be a little
> slower than
> direct import. However, most of the performance difference comes from
> the adding books process having an optimized implementation for finding
> duplicates -- I'll port that over to copy to library someday, but in the
> meantime you could just turn off checking for dupes when copying to
> library in Preferences->Adding Books.
>
> And note that importing directly from the source library folders will
> not lose any metadata provided that you run Library maintenance->Library
> metadata backup stats and wait for the backups to be completed (this
> causes the aforementioned opf files to be written out).
>
> --
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1593027
>
> Title:
> Copy to library takes 30 times longer than import
>
> Status in calibre:
> New
>
> Bug description:
> Calibre 2.58 on Ubuntu 14.04.
> I have a large library >450k books. When I import books, I import into
> an empty library so I can edit metadata quickly. This includes, typically,
> switching Author and Title fields, correcting Authors with commas, setting
> language to English, eliminating dates from Author fields, etc. When
> finished, I can either import the books from the small library directory,
> or copy the books to the large library. The import loses some edits as it
> re-reads data from the files themselves. The library copy works better,
> but takes MUCH longer, like multiple days to import 4k files into the large
> library. I think the library copy should be faster, not much slower, as it
> should just be copying the metadata from the database to the other
> database. The import is re-reading the files and getting bad data again.
> The correcting edits then take much longer, as updating the large library
> takes a minute or so for each individual edit.
>
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