OK, I am posting this as just me, not who I work for. :)

First, tell me who the person is that will actually ready that huge report? Must be one of the fastest speed readers in the world.

OK, So first, reports like these should be run over-night, not as ad-hoc.

2. There are products out there that generate reports like these, not necessarily in Java (did I just say that). Anyway they are products designed specifically for these types of reports, and therefore are "the right tool for the job" and not trying to pound a square peg into a round hole with a straw.

3. You might want to handle the data in batches, only bring down enough records at a time to do one page, then release that data to free up memory, and get the next page, and build up the report like that to stay away from out of memory issues. Now this will slow it down, but then again at this point you don't even get the report done.

Personally, I'd look for a product that does huge reports, that that is what they were built for, rather than forcing a bad solution.

Thanks

Mark