I am working with a system with 8 million rows in the acs_objects table. It is Oracle, so that might not say much about PG. For running reports, you should check out my cronjob package. This is relatively nice for manager types. It sends an html formatted email of the sql query, or for more heavy duty action, you can run any script or source a tcl file as well. It is in the OACS4.5 release. One nice thing is that it can run this whenever you want, or you can schedule it like cron, for daily, weekly, day of the week, or monthly reports, down to the minute.
