There's probably no better language on earth to build a data warehouse in than java yet i fully expect to see a BI book on Javascript OLAP technologies within my lifetime.
You use what you grow up with.
Because so many data warehouses has been built in it. Most significant problems have been solved traditional star schema/snowflake schema fact table oriented systems. And a change in language ins't going to open new doors that otherwise remain closed now.
Not sure I agree. SIMD instructions, vectorized query, and low-level memory management are hard to implement in Java. Plus there's genuine uncertainty about the future of the language. I would not implement a new data warehouse in Java at this point.
Intel and Linaro have contributed SIMD support, although it might be harder than using something like C++.
Not only is the language open source, while during Sun days it was only free beer, there are several contributors, and Microsoft has acquired jClarity, started contributing to OpenJDK, gives parity with .NET tooling on Azure, alongside Red-Hat supports Java on VSCode.
Ah, even Java has had more talks at Build 2020 than F# or VB.
The only uncertainty is from the anti-Java, Oracle hating crowd, for everyone else, companies using IBM, Red-Hat, Adobe, SAP,.... products, it is business as usual.
