So if someone creates a new instance and subs to a community in another instance they won’t see the community history?
Correct. It does (sometimes) backfill a a page of old posts on first subscriber, but zero comments. There is no backfill procedure for new servers.
Right now Lemmy has pretty serious bugs, such as not sending comment deletes to all servers subscribed to a community. So things like backfill aren't getting as much attention because it's hard to even keep servers consistent with new content.
Can I just remove the problem instances from the instance table?
that might have unintended side-effects. You have subscribers in your database that are tied to these instance rows, not sure what it would do to the joins.
If you are looking at solutions this drastic, perhaps just add them to your federation blocked list?
your server isn't going to send copies to other servers unless an account on that remote server subscribes. You said you created a new community, nobody is going to be subscribed.
If you are getting pending to every server you try, your proxy (typically nginx) config might be the problem. You should maybe try some of the curl test to federation endpoints from an outside box and see if something isn't blocking the connection.
Also note that in 0.18.2 (and any version since June 23) federation of mod removal and user delete of a post isn't working beyond 2 servers in field testing. It works for the user who removes it, their own server, and the community home server, but it is not shared to the remaining servers if the user doesn't happen to be directly on the community home server. So some other servers will still see the post. Same goes for comments. There are multiple open issues on GitHub. https://github.com/LemmyNet/lemmy/issues/3625
If anyone finds where this is in the code, please share. I'm sure some non-Lemmy code will allow longer, so I'm guessing it is only a input restriction... and someone could always hack their lemmy to allow longer. I don't suspect it is the database that has any limit.
And if it fails, I read somewhere that there is no handling in place, so it falls into void.
That is true in the current design, but in studying the actual outcomes, delivery-failures are not happening nearly as much as the problems with deletes and moderation.
I've been comparing servers for posts and comments for weeks, with 0.18.2 versions in the field - the majority of current inconsistencies are logic problems in the code that never even attempts to send (like deletes only going to 2 of 50+ servers).
Since 0.18.2 has been deployed by the bigger servers, the speed of propagation is really not much of an issue. The problem is a bug was introduced for posts on June 23, and for comments it seems that perhaps it has never worked. See my other comment for details.
For posts, I have been working on it this week and found that it has been broken since June 23 commit. Posts don't even get removed on the home server with 0.18.2, a fix is already waiting for acceptance: https://github.com/LemmyNet/lemmy/pull/3613
As for comments, with 0.18.2 - it depends where the delete is done. If you are on a remote instance from the community, the comment will be deleted on 2 servers, but no more. The local instance you use will delete, as will the community home, but it seems to me there never was any code to distribute deletes to subscribed servers: https://github.com/LemmyNet/lemmy/issues/3625
It also impacts moderators removing posts and comments. As these internally are similar to deletes. !asklemmy@lemmy.ml is one of the communities that has a lot of moderator removals due to people confusing the purpose of it as a technical support forum, and you can see servers not getting the mod removals frequently.
lemmy-ui is pretty bad about not returning the error code to you and just spinning icon. Maybe the person has blocked you? Maybe the post is locked now? Maybe the language setting conflicts with community? Maybe you are banned in community? It's really bad about not reporting the error. There are test communities, !test@lemmy.ml
is it only images? Can API clients get comments, posts, users, communities?