> > MayVACUUM FULL on a table improve perfromance of the system?
>
> No, it will make things worse.
???
Why?
"The FULL option is not recommended for routine use, but might be useful
in special cases. An example is when you have deleted or updated most
of the rows in a table and would like the table to physically shrink to
occupy less disk space and allow faster table scans"
This is for 9.0.
For 8.4 I think the indexes on the table could grow; but seq scan on the
table will be faster than with a plain vacuum...