Re: shared-memory based stats collector - v70

On Wed, Jul 20, 2022 at 11:35 AM Greg Stark <stark(at)mit(dot)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.

[1]
https://www.postgresql.org/message-id/flat/4E72940DA2BF16479384A86D54D0988A567B9245%40G01JPEXMBKW04