Which version of Java does datomic cloud run? 8?

There is now a published transcript for Rich Hickey's talk on Datomic Ions that he presented at clojure/nyc on Sep 12, 2018. If you have a better source for images of some of the slides, or know what he was saying in a few parts I couldn't understand marked "tbd", please open an issue or PR to improve it: https://github.com/matthiasn/talk-transcripts/blob/master/Hickey_Rich/DatomicIons.md

Hi, out of curiosity is there any reason datomic chose gzip over any other compression format?