1. ActiveRecord is extremely troublesome but not because of bandwidth. Sure, data movement is a performance headwind, but not the end of the world (in a row sto

1. ActiveRecord is extremely troublesome but not because of bandwidth. Sure, data movement is a performance headwind, but not the end of the world (in a row store all the data is adjacent anyway). Active record problematic because of its non-immutable nature. You cannot copy and mutate rows without weird side effects (in Spring for sure), which leavers you with an inherently imperative interface to your DB. 2. REST does not insist you fetch whole rows. You can have field masks with REST, it's inherently untyped, there is literally nothing preventing you adding that performance optimization if you need it, in a backwards compatible way (add the field mask query param later when you need it). https://developers.google.com/slides/how-tos/field-masks https://developers.google.com/slides/how-tos/field-masks