First step is to move posts from the archive database back into the regular one:
insert into ipb.posts
Replace ipb and ipb_archive with the correct database names for your installation.
You can restrict this to specific forums only by adding where archive_forum_id= X to the query (including the ones below).
The topics table need to be updated to reflect the change:
update ipb.topics set topic_archive_status=0
Then finally the archive table can be purged to save database space:
truncate table ipb_archive.forums_archive_posts
If you used a forum based restriction then adapt the query like so:
delete from ipb_archive.forums_archive_posts where archive_forum_id=X
Your topics should now be unarchived. If you're using any cache mechanism give those a refresh.
I've tested this on my very large boards where the combined posts table is over 9GB. Remember to check your MySQL query time limits so it doesn't get killed during the process.
I reported the session problem as a bug but it was ignored. Please help by posting your support there so they take it seriously!
While it's true that session-bound caching seems counter-productive since each guest will get served up a different page, for a high traffic environment where a lot of users log in the session hijacking risk is too much of a problem.
I think that's a very redundant method just to avoid the session mess caused by the IPB developers.
This creates correctly identifies mobile devices and uses the session token as part of the cache key - the importance of this is that without it, a guest who subsequently logs in can have their login hijacked by the next guest.
I very much doubt IPB developers can create a better framework than Twitter.
The benefit of Twitter Bootstrap is that because it's so popular there is a lot of support for it - many templates already exist that give a unique look and feel plus the design is very intuitive which allows people to make adjustments and modifications very easily. It is a rock solid framework that works brilliantly across all modern web browsers and devices.
IPS should seriously consider hosting their code on Github so people can fix all the bugs. I will be more than happy to sign a CLA before I submit code or even have access to the repo, seeing as they might not want to make it public.