Thanks a lot Before I thought wiki stores only diff s between versions As we can think that the most simple compression method is saving the diff sections For example in order to save 1000 1003 1005 1021 1240 1241 we only needed to save 1000 3 2 16 1240 1 and this is indentical to the basic of image compression like jpeg or motion compression like mpeg In order to save motion pictures mpeg used I frame P frame P frame I frame P frame so I was suprised to hear that wiki saves all the verion in full text format Anyway thanks It would be great to have a page something like wikipedia wikipage storage format that explains in detail how the wikipedia saves its every pages of every version in detail and how the editing warrings edit battle effects on the storage usage and how a single character addition effects on the storage usage etc If you had some authority on wiki and knew the stroge mechanism of wiki how about to edit that page Just a thought Anyway thanks