I'm limiting my choices to open source with good explanatory write-ups or presentations. Graphite for "simple" time series storage: https://www.aosabook.org/e

I'm limiting my choices to open source with good explanatory write-ups or presentations. Graphite for "simple" time series storage: https://www.aosabook.org/en/graphite.html https://www.aosabook.org/en/graphite.html HLL datatype (PFCOUNT, PFADD, PFMERGE) in Redis for counting unique items in a set: http://antirez.com/news/75 http://antirez.com/news/75 Data structures and algorithms that make Lucene & Elasticsearch fast (video): https://youtu.be/eQ-rXP-D80U https://youtu.be/eQ-rXP-D80U