Re: [pgsql-advocacy] Unlogged vs. In-Memory

Robert Haas <robertmhaas@gmail.com> writes:
> Basically, for every unlogged table, you get an empty _init fork, and
> for every index of an unlogged table, you get an _init fork
> initialized to an empty index.  The _init forks are copied over the
> main forks by the startup process before entering normal running.

Let's call that metadata.

> Well, we could certainly Decree From On High that the _init forks are
> all going to be stored under $PGDATA rather than in the tablespace
> directories.  That would make things simple.  Of course, it also means

And now you need to associate a non volatile tablespace where to store
the metadata of your volatile tablespace where you want to store
unlogged data.  And we already have a default tablespace, of course.

Regards,
-- 
Dimitri Fontaine
http://2ndQuadrant.fr     PostgreSQL : Expertise, Formation et Support