What category? The examples you used are formally relational databases. We can certainly talk about common use-cases for certain specific database vendors and p

What category? The examples you used are formally relational databases. We can certainly talk about common use-cases for certain specific database vendors and products but that's not the same as the underlying type. For example, here's Pinterest handling time-series data on Hbase: https://medium.com/pinterest-engineering/pinalyticsdb-a-time-series-database-on-top-of-hbase-946f236bb29a https://medium.com/pinterest-engineering/pinalyticsdb-a-time... There's a big difference and muddying the definitions with marketing jargon ends up causing too much confusion in this industry.