We have a problem with export excel file that contains 12 mil cells.
One question: WHY?!
Edit: And don't say "It's a requirement." because I can write a "requirement" stating "I require that my coffee machine also heats the water for my bathtub." ... while technically possible it's still pointless and a rubbish requirement.
Have a read of this thread, and I will quote my contribution to it directly here:
If you need to get so much data out to a file, do it a different way. Use an ODBC or JDBC connection into the BI Server directly, or go direct to the database. Trying to export that much data through the OBIEE front end is just a Bad Idea. If it ever works at all, it's going to kill your system performance. Another reference for you to read: OBIEE Performance Analytics: Analysing the Impact of Suboptimal Report Design
What point would you consider being too much data to export normally? 12 mil cells is a really high figure. What about 1 mil, 500k, 50k?
I'd look more at why it's being exported. If it's to then use it in a tool to do something that OBIEE can do natively, I'd discourage the export in the first place. If it has to be exported for a 'valid' reason then I'd look at the most efficient way to get it out - and an Excel generated from Answers is rarely the most the efficient. Normally you'd look at least CSV, if not BI Publisher, or even ODBC/JDBC connection directly into the BI Server so as to by-pass the Presentation Services entirely. All of those enable you to utilise the RPD metadata - but if you don't really need that then just ignore OBIEE entirely and save resource by hitting the DB directly for the export.
So "too much" is less quantitive and more subjective.
The point isn't how much. The point is: Why do it in the first place? What for? In order to achieve which goal?
And again: "Because it's a requirement isn't an answer.