I offer possibility #4 - this is totally nuts. The feds can't even redesign the IRS computer systems, where 90+percent of the data coming in has a matching key, either SSN or TIN. And they think they can create a massive database, probably on the order of tens of petabytes in scale, that can allow them to wallow through thousands if not millions of data feeds that must be matched without a common linking key, and use data modelling of a sophistication that does not yet exist, to find a couple of terrorist cells, when they couldn't even friggin' run a SQL query on the DC sniper database to determine that they should check out that Caprice that was entered several times?
What the feds need to do is can the crap. Their problem is not a lack of a huge database. Their problem is not a lack of information. Their problem is the stinkin' PC mindset and reliance on technology over old-fashioned human intel, investigation and intuition. They don't need a bigger database. They need an attitude adjustment.