Monarch: Google’s Planet-Scale In-Memory Time Series Database [pdf]
Interesting that this paper contains hard numbers hinting at Google's absolute scale. They say Monarch has 144000 leaves. Even if each leaf is assigned only 1 CPU core -- which is probably a low estimate because who would do that? -- that makes Google's monitoring stack a Top 100 supercomputer.The only other places I've seen Google give out hard numbers were a presentation by Jeff Dean mentioning map-reduce core-years consumed per day, and a footnote in a paper that mentions how much CPU time Google Exacycle gives away to scientific computing every day. All of these calibration points are eye-opening.