Hi,
> Is there any software for postgresql like innotop for mysql ?
I am not sure. A while ago I saw a demo of pgtop, but I haven't
actually used it. I forget exactly who created it, but I think that
at least Selena Deckelmann had contributed to it.
> I would like to monitor postgresql with Cacti, but i didn't find any
> module for that in cacti, do you know a module for that ?
No, but perhaps it would be a good thing to add to
http://code.google.com/p/mysql-cacti-templates/ (which despite the
name has high-quality templates for quite a few different things).