On Wed, Jul 20, 2022 at 11:35 AM Greg Stark <stark@mit.edu> wrote:
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.
I think efforts to do such a thing have gotten caught up in solving issues around visibility and managing the relationship between local and global caches [1]. It doesn't seem like the primary technical concern was memory usage.
