On Mon, 2003-07-28 at 11:04, Tom Lane wrote: > Alvaro Herrera <[EMAIL PROTECTED]> writes: > > Vacuum full locks the entire table and moves tuples between pages. It > > leaves all pages full of tuples (except, obviously, the last one), so it > > doesn't need to record them in the FSM. > > This is overoptimistic :-(. VACUUM FULL cannot necessarily compact the > table completely, and so it will record free space in FSM (if there is > any worth recording). An example situation is that page 1000 may > contain a very large tuple, which will not fit on any earlier page. > Once VACUUM FULL discovers this fact, it will not bother shuffling > tuples on earlier pages, since it's not going to be able to truncate the > table to less than 1000 pages. There may nonetheless be enough space > available in earlier pages to store thousands of smaller-sized tuples. >
Isn't it possible that the reshuffling of tuples before page 1000 could open up enough space to move the overly large tuple? Robert Treat -- Build A Brighter Lamp :: Linux Apache {middleware} PostgreSQL ---------------------------(end of broadcast)--------------------------- TIP 8: explain analyze is your friend