Few distributed SQL DB vendor information - http://www.infoq.com/news/2013/11/sql-newsql-nosql

Approximation DB - http://highscalability.com/blog/2016/11/28/how-to-make-your-database-200x-faster-without-having-to-pay.html

Discuss and compare difference technology of querying journey(log) data - http://www.infoq.com/cn/articles/trillion-log-and-data-storage-query-techniques

SAP HANA - https://www.google.com/search?q=sap+hana