Re: Big 7.1 open items

Don Baccus  writes:
>> This isn't any harder for md.c to deal with than what we do now,
>> but by making the /N subdirectories be symlinks, the dbadmin could
>> easily arrange for extension segments to go on different filesystems.

> I personally dislike depending on symlinks to move stuff around.
> Among other things, a pg_dump/restore (and presumably future 
> backup tools?) can't recreate the disk layout automatically.

Good point, we'd need some way of saving/restoring the tablespace
structures.

>> We'd still want to create some tools to help the dbadmin with slinging
>> all these symlinks around, of course.

> OK, if symlinks are simply an implementation detail hidden from the
> dbadmin, and if the physical structure is kept in the db so it can
> be rebuilt if necessary automatically, then I don't mind symlinks.

I'm not sure about keeping it in the db --- creates a bit of a
chicken-and-egg problem doesn't it?  Maybe there needs to be a
"system database" that has nailed-down pathnames (no tablespaces
for you baby) and contains the critical installation-wide tables
like pg_database, pg_user, pg_tablespace.  A restore would have
to restore these tables first anyway.

> Make the code that creates and otherwise manipulates tablespaces
> do the work, while keeping the low-level file access protocol simple.

Right, that's the bottom line for me.
		regards, tom lane