Of course fake volume

https://www.newsbtc.com/2018/12/20/only-coinbase-binance-have-300k-users-fake-volume-on-most-crypto-platforms

Most of these others need eyeballs, but don't offer much value in a bear Market.  Click bait everything as a thing these days. 

ElasticSearch at CoinBase

https://youtu.be/u5j0MOpIkV0

ElasticSearch and big data on Coinbase.  Cool presentation on how they implented ElasticSearch.