Thread:Project:Support desk/Page history in bytes/reply (2)

In 1.19 #15 from that diagram should be present. However #14 (the total number bytes) was not introduced until a later version of MediaWiki

Less likely, but also possible. If certain fields are not populated in the database, they won't show up properly. This can be caused by not properly running update.php properly. This includes the rev_parent_id field, and the rev_length field. These can be updated by running the scripts populateParentId.php and populateRevisionLength.php respectively [both usually get automatically run during the upgrade process]. (In your case, I think you just need a newer version of MediaWiki, but if all else fails, you can also try those scripts).