13

I'm a bit confused by this Q&A pair:

https://physics.stackexchange.com/questions/253062/dimensional-analysis-problem

(10k on Physics, or dev team.) The question looks like this:

enter image description here Of note:

  • The answer was posted 10 minutes after the question.
  • The answer was upvoted at some point.
  • The question was closed about an hour afterwards.
  • The question was auto-deleted some ten days later.
  • The answer was deleted by a moderator about two weeks after that.

... say what? How did the answer get deleted way after the question? And, moreover, how did the question get RemoveAbandonedClosed'd if it had an upvoted answer? It gets a bit weirder if you go to the answer's timeline to investigate:

enter image description here How come a deleted post has as its last entry an 'undeleted' action?

My guess at what happened is that

  • The mod deleted the answer right after the question closure (site policy goes against providing full answers to homework questions).
  • The question was then auto-deleted by the Community user.
  • The mod later came back and undid the delete vote on the answer.

I̶ ̶h̶a̶v̶e̶ ̶a̶s̶k̶e̶d̶ ̶t̶h̶e̶ ̶m̶o̶d̶ ̶o̶n̶ ̶c̶h̶a̶t̶ ̶b̶u̶t̶ ̶h̶a̶v̶e̶ ̶y̶e̶t̶ ̶t̶o̶ ̶h̶e̶a̶r̶ ̶f̶r̶o̶m̶ ̶h̶i̶m̶.̶ ̶I̶'̶m̶ ̶n̶o̶t̶ ̶s̶u̶r̶e̶ ̶w̶h̶a̶t̶ ̶t̶h̶e̶ ̶p̶o̶i̶n̶t̶ ̶o̶f̶ ̶t̶h̶e̶ ̶u̶n̶d̶e̶l̶e̶t̶i̶o̶n̶ ̶w̶a̶s̶,̶ ̶a̶s̶ ̶i̶t̶ ̶d̶o̶e̶s̶ ̶n̶o̶t̶ ̶i̶m̶p̶a̶c̶t̶ ̶t̶h̶e̶ ̶p̶o̶s̶t̶ ̶a̶t̶ ̶a̶l̶l̶,̶ ̶b̶u̶t̶ ̶i̶f̶ ̶i̶t̶ ̶c̶a̶n̶ ̶h̶e̶l̶p̶ ̶t̶h̶e̶ ̶a̶n̶s̶w̶e̶r̶e̶r̶ ̶a̶v̶o̶i̶d̶ ̶a̶ ̶b̶a̶n̶ ̶t̶h̶e̶n̶ ̶s̶u̶r̶e̶,̶ ̶g̶o̶o̶d̶ ̶t̶h̶i̶n̶g̶. This was done because site policy asks for temporary deletion of answers that contain full answers to homework questions, and the mod did the undeletion by routine, to make sure the answer was available if the question was ever undeleted and to ensure that the deletion did not prejudice the poster in terms of question or answer bans.


More than clarification on the timeline, though, I have an issue with how the data is presented. Regardless of what happened, the page should be able to convey its story unambiguously, and here that story as presented is inconsistent.

  • If indeed the answer deletion was undone by the mod, why is the post still marked as deleted? The answer should not be visible because its parent thread is deleted, but in such cases (example) the answer is marked simply 'deleted' (with no attribution) at the time of the question deletion.
  • If that's not what happened, then what's the deal with that last undeleted entry in the timeline?

Either way, it feels like a bug in the software that produces these deletion reports.

... and, while I'm here, why is there even an undelete action on that answer? There's no way to bring it back without reviving the question, so why not skip that and point users to the undelete button on the question itself? (e.g. gray out that button on the answer, with a tooltip 'To undelete this thread, vote to undelete the question', or something; it's a 10k+ page so users that see it understand the mechanics.)

11

Your sequence of events was correct thus far.

The moderator did undelete the post manually (no idea why). However, there is an automated process that silently wipes out all answers on a deleted question. This process essentially just marks every answer as deleted, to make sure they all are, and runs every couple of hours (?). So when the moderator undeleted it, the system simply marked it as deleted again shortly after.

This silent deletion mechanism does not add a deletion history event because doing so on every answer to a deleted question would clog up the database and the revision history with useless information. It also doesn't make much sense in the answer's history since the answer's deletion is only of direct consequence from the question's deletion. The event occurred on the question, and not the answer.

Imagine one of those questions which gets deleted/undeleted multiple times because the community cannot decide if it should stay or go. Now imagine those deletion/undeletion events in the question's history being duplicated onto every single answer on the question. What a mess that would be.

When the answer ends up silently deleted again, it uses the latest deletion event for its information and, if none exists, displays a simple "deleted some time ago" message instead. Since the latest deletion event is the moderator deleting it initially, that's what gets displayed. This has been reported to us as a bug many times in many different forms, but has never been fixed.

  • 1
    Thanks for the explanation - but I still think it's a bug. It's complicated to decide what that line should report (deleted by the mod? → has been undone. deleted with the question? → answer was deleted at the time), but the current display is completely fictional: "deleted by the mod on June 1" never happened. Have it say "deleted on June 1" and you're on the sweet spot - add a flag by the silent deletion that's used for this, and there's no need to clobber the answer's timeline. – E.P. Jun 7 '16 at 15:33
  • Oh yes it is a bug, we just haven't come up with a proper fix for it. – animuson Jun 7 '16 at 15:34
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    Oh, OK, thanks for that little bit. "Has been reported as a bug" → "We think is a bug, too" is a big step. But you're right, it's not a particularly easy problem. – E.P. Jun 7 '16 at 15:36
  • The mod has confirmed the manual undeletion and the motivation (see question edit). One final thing - can you clarify what's up with that pending undelete vote on the answer? Would it have an effect if more people voted? Was the vote cast by the mod and lingers on for some bizarre reason? Or was it someone else? Is this buggy behaviour? If it was someone else, was it before or after the manual undelete? – E.P. Jun 8 '16 at 13:26
  • @EP It's another part of the same bug that occurs when there are previous deletion events but no current deletion event. Would theoretically be fixed if we ever fixed the display issue. – animuson Jun 9 '16 at 14:25

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