@peterT
My database was 38 GiB before i started compressing my files. If i concentrate on biggest files, i think i can quickly reduce it to 30 GiB, and maybe 20 GiB if i spend more time. I reduced some epub from 150 MiB to 10 MiB, but it's quite the exception. Most of my work is on PDF files: depending on the file, i can reduce it from 2 to 10 times.
@kovidgoyal
yes, but still no

It seems other people have the same trouble:
https://www.mobileread.com/forums/sh...125428&page=68 (see nixsee's post). Maybe 'ill try to apply this patch later.