(c) we are considering whether to use an in-place heap update for the relation stats, so that a large restore doesn't bloat pg_class -- I'd like feedback on this idea
I'd also like feedback, though I feel very strongly that we should do what ANALYZE does. In an upgrade situation, nearly all tables will have stats imported, which would result in an immediate doubling of pg_class - not the end of the world, but not great either.
Given the recent bugs associated with inplace updates and race conditions, if we don't want to do in-place here, we should also consider getting rid of it for ANALYZE. I briefly pondered if it would make sense to vertically partition pg_class into the stable attributes and the attributes that get modified in-place, but that list is pretty long: relpages, reltuples, relallvisible, relhasindex, reltoastrelid, relhasrules, relhastriggers, relfrozenxid, and reminmxid,
If we don't want to do inplace updates in pg_restore_relation_stats(), then we could mitigate the bloat with a VACUUM FULL pg_class at the tail end of the upgrade if stats were enabled.
pg_restore_*_stats() functions. But there's a lot of overlap, so it may be worth discussing again whether we should only have one set of functions.
For the reason of in-place updates and error tolerance, I think they have to remain separate functions, but I'm also interested in hearing other's opinions.
