SlicingDice founder here. We built SlicingDice exactly for this kind of necessity, very fast user segmentation. Actually, we just developed it because we didn't find any other solution that could support our needs.
https://blog.slicingdice.com/why-we-built-slicingdice-1beffc...
User segmentation was actually the original use case that prompted Pilosa's development! Segmenting hundreds of millions of users with tens of millions of potential attributes.
Very nice job.
Looks like we were trying to solve the same problem (user segmentation), in the same industry (DMP), at the same time (2013-2016). LOL.
I'm the founder of a DMP too.
https://blog.slicingdice.com/why-we-built-slicingdice-1beffc...
I will email you guys.
[1] https://code.facebook.com/posts/382299771946304/audience-ins...