Itagaki Takahiro wrote:
> We still need traditional VACUUM FULL behavior for system catalog because
> we cannot change relfilenode for them. Also, VACUUM FULL REPLACE is not
> always better than traditional VACUUM FULL; the new version requires
> additional disk space and might be slower if we have a few dead tuples.
Tom was saying that we could fix the problem that relfilenode could not
be changed by having a flat file filenode map. It would only be needed
for nailed system catalogs (the rest of the tables grab their
relfilenode from pg_class as usual) so it wouldn't have the problems
that the previous flatfiles had (which was that they could grow too
much). I don't recall if this got implemented (I don't think it did).
As for it being slower with few dead tuples, I don't think this is a
problem -- just use lazy vacuum in that case.
I also remember we agreed on something about the need for extra disk
space, but I can't remember what it was.
--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.
