However, the firm declined to do so, effectively saying it was too difficult to locate the info within its humongous data warehouse.
Come on FB you knew this was going to happen and you are telling us that you have no easy way of doing this or that you didn't invest in the infrastructure to make this possible.
noting that this kind of architecture was necessary due to the sheer volume of data created
The sheer volume of data slurped.
Facebook simply does not have the infrastructure capacity to store log data in Hive in a form that is indexed by user in the way that it can for production data used for the main Facebook site
You say you can't locate the information but then say you don't have the capacity to do it. Anyone would think that you're making excuses because you want anyone to know the sheer scale of your slurping.