Pilosa: open source, distributed bitmap index in Go
This is exactly something I've been looking for to experiment with user segmentation, but crucially for fast, ad-hoc segmentation. Seems to bear some similarity to what Facebook [1] does for its audience insights.<p>[1] <a href="https://code.facebook.com/posts/382299771946304/audience-insights-query-engine-in-memory-integer-store-for-social-analytics-/" rel="nofollow">https://code.facebook.com/posts/382299771946304/audience-ins...</a>