I opted to store feather for one particular reason. You can open it using mmap and randomly index the data without having to load it all in memory. Also the data I have isn't very compressible to begin with, so the cpu cost vs data savings of parquet don't make sense. This only makes sense in that narrow use case.
I'm doing the same. It's also quite nice for de-duplication, a lot of operations on our data happen on a column basis, and we need to assemble tables that are basically the same, except for one or two computed columns. I usually store all columns in a separate file, and assemble tables on the fly, also memory-mapped. Quite happy with being able to do that. Not sure how easy that would be with parquet.
