[glogla]

RedShift, Snowflake, Citus, Greenplum and Athena are OLAP engines, but not real-time focused. For this one, it is more similar to Druid, ClickHouse or RockSet.

The 1.0 version of Pinot seems to bring a lot of maturity, they seem to have added new engine that can do joins now. I'm not sure how stable it is, but it seems interesting.

As for what is this kind of database usedful for, this is for operational analytics on large data that also update in real time. In my domain that would be things like having insight into large supply chains or manufacturing operations, like power plants or factories, just in general for monitoring stuff. I know it's also used in security and finance (for fraud).