On Jan 17, 2011, at 8:11 PM, Robert Haas wrote: > On Mon, Jan 17, 2011 at 7:56 PM, Jim Nasby <j...@nasby.net> wrote: >> - Forks are very possibly a more efficient way to deal with TOAST than >> having separate tables. There's a fair amount of overhead we pay for the >> current setup. > > That seems like an interesting idea, but I actually don't see why it > would be any more efficient, and it seems like you'd end up > reinventing things like vacuum and free space map management.
The FSM would take some effort, but I don't think vacuum would be that hard to deal with; you'd just have to free up the space in any referenced toast forks at the same time that you vacuumed the heap. >> - Dynamic forks would make it possible to do a column-store database, or at >> least something approximating one. > > I've been wondering whether we could do something like this by > treating a table t with columns pk, a1, a2, a3, b1, b2, b3 as two > tables t1 and t2, one with columns pk, a1, a2, a3 and the other with > columns pk, b1, b2, b3. SELECT * FROM t would be translated into > SELECT * FROM t1, t2 WHERE t1.pk = t2.pk. Possibly, but you'd be paying tuple overhead twice, which is what I was looking to avoid with forks. -- Jim C. Nasby, Database Architect j...@nasby.net 512.569.9461 (cell) http://jim.nasby.net -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
