Re: shared-memory based stats collector - v70

On the one hand the rest of Postgres seems to be designed on the
assumption that the number of tables and database objects is limited
only by disk space. The catalogs are stored in relational storage
which is read through the buffer cache. On the other hand it's true
that syscaches don't do expire entries (though I think the assumption
is that no one backend touches very much).

It seems like if we really think the total number of database objects
is reasonably limited to scales that fit in RAM there would be a much
simpler database design that would just store the catalog tables in
simple in-memory data structures and map them all on startup without
doing all the work Postgres does to make relational storage scale.