I am sorry for stepping in, but maybe I did not understand fox reply.
My situation is, I moved hosting, so I had to reinstall tt-rss, which meant all articles for all feeds have been refetch. In my mind, I had to "mark as read " -> “older than a week” but it does not work.
So I thought I could click on a category, sort by oldest, and having “Automatically mark articles as read” enabled, I would scroll untill I find a post to a date older than the one of the new installation.
As you can see from the screenshot, it does not work, because even though I disabled feeds’ grouping, the sort is unexplainable.
#1 and #2 could be fine if feeds were grouped (which is not), but it does not explain #3, because the feed start with k and the date is older than #2 but newer than #1
Then suddenly out of nowhere comes #4, which is older than #3 but all his brothers are above.
I am running b6a021461d2ea54a91ce77c58591ad2ead35abdc on PostgreSQL
On a side note, if I group feeds, the order is respected within the feed, but I can not figure out which feed tt-rss decide to show first