> … applying semantic indexing … to the sparse data in a way that was both fast and let us store hundreds of millions of documents in memory on fairly normal hardware.

Fascinating. Would you mind sharing more, some links / white papers?

We did something similar with ScaleText.ai (as a step-up from Gensim), I'd be curious to compare notes and perf numbers. Drop me an email at [email protected] if interested. Thanks!