Replying to @LeaVerou
Not pg-specific but if it has logical subtrees I've done similar using clarinet to break into pieces before loading. github.com/dscape/clarinet
Thread · 3 tweets · 19 Jul 2017
Not sure if clarinet is current state of the art. Anything that will give you the JSON SAX-like ought to work.
If you need to store the whole thing as a single record though, not sure!