On Sun, 2002-09-29 at 19:28, Tom Lane wrote:
> Hannu Krosing <hannu@tm.ee> writes:
> > The initial Postgres design had a notion of StorageManager's, which
> > should make this very easy indeed, if it had been kept working .
>
> But the storage manager interface was never built to hide issues like
> tuple representation --- storage managers just deal in raw pages.
I had an impression that SM was meant to be a little higher-level. IIRC
the original Berkeley Postgres had at one point a storage manager for
write-once storage on CDWr jukeboxes.
the README in src/backend/storage/smgr still contains mentions about
Sony jukebox drivers.
http://www.ndim.edrc.cmu.edu/postgres95/www/pglite1.html also claims
this:
Version 3 appeared in 1991 and added support for multiple storage
managers, an improved query executor and a rewritten rewrite rule
system. For the most part, releases since then have focused on
portability and reliability.
> I doubt it would have helped in the least for anything we've been
> concerned about.
Yes, it seems that we do not have a SM in the semse I hoped.
Still, if we could use a clean SM interface over old page format, then
the tuple conversion could be done there.
That of course would need the storage manager to be aware of old/new
tuple structures ;(
-----------------
Hannu