Why is there a discrepancy in the number of comments between the same thread on different instances? And other fediverse confusion.

3 years ago by inmoderation to c/meta

(Please correct any misunderstandings below.) From my limited understanding of the fediverse, for each thread that exists, every instance will host its own version of it. This instance-specific version will collect comments left from users from all instances in the "world" (whatever that means here). The exception is if instances block other ones.

But what about this random thread:

https://sopuli.xyz/post/683221

https://lemm.ee/post/30817

The first is the original (which is confusingly posted in a community at Beehaw, but I believe the original is at sopuli.xyz because the user is registered there). The second is the version on lemm.ee. Why do I see 13 comments for lemm.ee and 18 for sopuli.xyz? One comment that I do not see on lemm.ee is by a user on sh.itjust.works. This is not a blocked instance. Is it because lemm.ee needs to pull from all instances periodically, and this is just a cached version? If so, how often are these updates, and is there any way to see a timestamp of the cache for an individual post?

AFKBRBChocolate 4 points 3 years ago

I'm relatively new and still figuring things out, but I believe what happens normally is that, when you make a post in a community, the "true" version of that post is on the instances where that community lives. If your account is on another instance, your instance gets a copy of that post, where you make your comment, and then the instances synch up, putting your comment on the "true" version, and whatever other comments people have made from other instances to the "true" version get posted to your instance's copy of it.

That post was on a community on Beehaw, which has a long list of instances it's defederated from. A user from one of those defederated instances might see the post, and even comment on it, but their comment won't get synched up to the "true" version, so it won't get copied to other instances.

I didn't analyze all the comments and where they're from, but my guess is that the above is the underlying issue.

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inmoderation 3 points 3 years ago

Thanks, this might be on to something because I don't see a sh.itjust.works post on the lemm.ee version but I know beehaw defederated from them, and the community is a beehaw community. Maybe lemm.ee is pulling from beehaw.

But I don't think it fully explains the situation. Here's the post on beehaw:

https://beehaw.org/post/528754

For me that shows 17 comments, and I only see 13 on lemm.ee. But lemm.ee is defederated from fewer instances than beehaw, so what could explain that?

Edit: is it possible lemm.ee is simply not aware of all the instances?

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AFKBRBChocolate 4 points 3 years ago

You can see exactly which instances are federated or blocked from an instance by going to the instance with /instances. So for Beehaw it's https://beehaw.org/instances and for lemm.ee, it's https://lemm.ee/instances. It looks like they're both federated to each other.

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AFKBRBChocolate 2 points 3 years ago

Maybe lemm.ee is pulling from beehaw.

Oh, by the way, 100% it is. Beehaw has the true version, so everything is pulling from there.

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A_Very_Big_Fan 2 points 3 years ago

Is there a way to see what instances any given instance is defederated from? Or to see what instances any instance has defederated themselves from?

The structure of all this makes my head hurt lol. But I think I'm figuring it out....

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inmoderation 2 points 3 years ago

You can click "Instances" at the bottom of the page on lemm.ee to see what lemm.ee has blocked. But I don't know how to tell what instances have blocked lemm.ee.

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A_Very_Big_Fan 2 points 3 years ago

I see the linked instances but not the blocked ones. I think the thing that was confusing me is the search results not showing me communities that I know exist on other instances, even when the filter is set to "all"... I'm sure that will be ironed out over time, though

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A_Very_Big_Fan 1 point 3 years ago

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Maffrow 1 point 3 years ago

I’ve been seeing this quite a lot today and it’s also probably because I’m looking out for it. The posts I’ve seen and checked all had comments from users from Beehaw, Lemmy.world, kbin. The comments did not match up between viewing from here (lemm.ee) and the source post. I’m kinda putting it down to all of these instances getting hammered with signups and potential strain on the servers but I’m happy to be told that’s wrong.

I would guess that things will get better, sync faster and more consistent as time goes on.

If anyone has a better or more informed opinion as to why this is happening please comment as I’m trying to get a better understanding of all of this as the days go on.

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