On Wed, 4 Jun 2003, Shankar K wrote:
> hi all,
>
> I'm trying to evaluate the frequecy to run vacuum
> analyze on key tables. so if anyone could help me to
> interpret the output of vacuum analyze verbose output
> that would be great. below is the output of one of our
> major indexes.
>
> INFO: --Relation public.accounts--
> INFO: Index accounts_u1: Pages 1503; Tuples 231:
> Deleted 55448.
> CPU 0.01s/0.14u sec elapsed 0.15 sec.
> INFO: Index account_u1: Pages 1997; Tuples 231:
> Deleted 55448.
> CPU 0.01s/0.13u sec elapsed 0.15 sec.
> INFO: Index account_u2: Pages 2415; Tuples 231:
> Deleted 55448.
> CPU 0.00s/0.14u sec elapsed 0.30 sec.
> INFO: Removed 55448 tuples in 2367 pages.
> CPU 0.04s/0.11u sec elapsed 0.41 sec.
> INFO: Pages 11266: Changed 4, Empty 0; Tup 231: Vac
> 55448, Keep 0, UnUsed 205434.
> Total CPU 0.12s/0.56u sec elapsed 1.08 sec.
>
> thanks
> Shankar
>
Its actually quite simple from what I under stand.... (Not that I
know for certain someone will correct me if I'm wrong and I'm not an
expert)
Pages: Number of Pages used by Index (or table)
Tuples: Number of Records In table in use
Deleted: Number of Records just deleted in table
UnUsed: Number of Records In Table not in use currently. (I think vacuum
full should remove these)
Changed: Number of Records Changed (Not sure)
Keep: Number of Records to Keep (Not Sure)
CPU Time taken to complete vacuum.
So Tuples + Unused = Total Tuples used in table.
Hence (Tuples + Unused)/Pages = Number of Records per page hence record
size
If deleted gets too big you should be vacuuming more often
If unused gets too big try and increase your fsm size.
Or that is the way I under stand it. I'm now waiting for somone to
correct me.
Peter Childs