Re: Statistics Import and Export

>
>
> (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.