Right now, vectorization is ONLY used in Parquet reader and in-memory cache, other operators still work in one-row-at-a-time mode, but compiled into single (or

Right now, vectorization is ONLY used in Parquet reader and in-memory cache, other operators still work in one-row-at-a-time mode, but compiled into single (or a few) Java function(s), the intermediate results of these operators could be hold in CPU register or in stack. It's easy to be high performant and support complicated data types and expressions comparing to vectorized execution, so we (Databricks team) picked whole-stage code generation other than vectorized execution. disclaimer: I worked on whole-stage codegen and other performance related stuff.