Re: reading vacuum verbose output

Tsirkin Evgeny <tsurkin@mail.jct.ac.il> writes:
> INFO:  --Relation public.student2maslulsign_rashum_musmach_old--
> INFO:  Pages 906: Changed 0, Empty 0; Tup 846: Vac 0, Keep 0, UnUsed 96035.
>         Total CPU 0.03s/0.01u sec elapsed 0.04 sec.

> If there are unused tuples why i see the Changed 0 ?

Those are unused tuple slots, not tuples.  They can be re-used, but they
won't be reclaimed unless the page they are in is truncated from the
table.

> (Note :The db is vacuumed every ~5 hours ver 7.3)

It would appear that you need a round of VACUUM FULL to get these tables
back down to a reasonable physical size, and in future vacuum more often.
Check your FSM settings too.

            regards, tom lane