Yes, Ballista failed to gain traction. I think that one of the challenges was that it only supported a small subset of Spark, and there was too much work involved to try and get to parity with Spark.
The Comet approach is much more pragmatic because we just add support for more operators and expressions over time and fall back to Spark for anything that is not supported yet.
The Comet approach is much more pragmatic because we just add support for more operators and expressions over time and fall back to Spark for anything that is not supported yet.