Mario Weilguni <mweilguni@sime.com> writes:
> I think oracle does not do garbage collect, it overwrites the tuples directly
> and stores the old tuples in undo buffers. Since most transactions are
> commits, this is a big win.
... if all tuples are the same size, and if you never have any
transactions that touch enough tuples to overflow your undo segment
(or even just sit there for a long time, preventing you from recycling
undo-log space; this is the dual of the VACUUM-can't-reclaim-dead-tuple
problem). And a few other problems that any Oracle DBA can tell you about.
I prefer our system.
regards, tom lane