Re: Identifying diskspace leakage

On Friday May 14 2004 11:47, Jeffrey W. Baker wrote:
> > Is there a way to identify the numbers of unused tuples without
> > performing a VACUUM? Is it stored in a system table anywhere? Other
> > ideas on how to identify disk bloat short of forcing downtime?
>
> You can calculate the number of bytes per row, multiply by the number of
> live tuples (count(1) from table), and subtract that from the actual #
> of bytes in the on-disk representation. The difference is wasted space.

That works, but with umpteen clusters to manage, I'm really hoping for a
SQL-based check so it can be done remotely and non-interactively. Maybe it
is too much to keep track of, but it would be cool if VACUUM updated a
system table with the same info it spits out during verbose mode. That
would be very helpful in auto-identifying leakage and also a recent case
where the cpu:real time ratio during vacuum went thru the roof due to I/O
overload from leakage.