I have an LibreOffice Calc document (file.ods) with the size 71 Kb.
If I open it and modify something (even delete 1 cell) and then save, it comes with the size 78 Kb.
I'm sure that major version of LibreOffice didn't change since last saving (I use libreoffice-calc 1:5.1.6~rc2-0ubuntu1~xenial1 with Kubuntu 16.04.2 LTS).
I'm trying to investigate. If I create new OpenDocument Spreadsheet (newfile.ods), manually insert the data from old file into it and save (making sure that there are no invisible unused rows there), the newfile size is still 78 Kb.
What is the reason of such unexpected grow of file size? How to debug that?
Added: I've solved half of the problem (now gile grows from 71 Kb to 73 Kb): size could grow because of built-in thumbnail saving in libreoffice (when saving file, it puts a little graphical preview of spreadsheet in PNG format into *.ods file). If thumbnail shows area with colorized data, it could be at least 10 Kb, and if thumbnail shows area with a little text and no extra colors, it could be just 3 Kb. I turned off thumbnail saving by setting "GenerateThumbnail" into "false" (Tools → Options... → LibreOffice → Advanced → Expert Configuration). But the question is still actual: why does file.ods size increase, while there are no new extra data in it?