Merge duplicates duplicates attachments

Davidal

Hi. It's a great function of Zotero but I don't understand why merging the parent duplicate items also merges the PDFs. I see no point (other than preserving highlights/notes) to have two versions of the PDFs, which uses up cloud storage.

bwiernik

The two PDFs might not be identical (e.g., one might have annotations and the other not; one might be a supplement file), and there isn’t a reliable way to safely automatically pick only one PDF to keep, so Zotero is cautious and avoids data loss by keeping both.

Davidal

@bwiernik I understand, but if they are identical in name and size why keep both?

bwiernik

PDFs almost never are strictly identical (e.g., many library systems add a watermark when downloaded, so two copies of the same article won't be identical anymore). Zotero has discussed trying some degree of detecting whether files are identical, but the cases where it would work are uncommon enough that it hasn't been much of a priority.

midas0441

really? In 99% of duplicates that I deal with, I end up needing/wanting to keep only 1 of the PDFs. If the file has the same name and the same size (two easy things to check), the chances are incredibly high that 1 could be deleted, no? Alternatively, show a dialog box and ask the user. The dialog box could display scrollable previews of the 2 PDFs side-by-side.

brightj

But if the files are byte-for-byte identical, why does it keep both?

adamsmith

It shouldn't anymore - if files have identical checksums, the newer one (?) gets deleted on merge now.