This changes from storing only a single topic visit per user to just
storing all of them. I don't intend to keep all of these and will
probably find a way to "quantize" repeated visits soon. However, I want
to get an idea of the volume first, and also use this to see how the new
querying methods work in production.
On that note, I'm not sure that the LATERAL outer join is the best
method, but it seems interesting (and was kind of a pain in the ass in
SQLAlchemy), so we'll see how it looks.
As part of this, I also changed the method of adjusting num_comments on
past topic visits to be done entirely in triggers, instead of the
previous approach of doing it in _increment_topic_comments_seen().
However, this really just made me realize how incorrect this idea is and
how many edge cases can come up that will mess up the comment counters
on the visits (e.g. post a comment and then delete it immediately).
Hopefully this can go away in the somewhat near future with some other
changes to notifications.
Deimos
5495d5b4d2