pg_dump object sorting

I have been looking at refining the sorting of objects in pg_dump to 
make it take advantage of buffering and synchronised scanning, and 
possibly make parallel restoration simpler and more efficient.

My first thought was to sort indexes by <namespace, tablename, 
indexname> instead of by <namespace, indexname>. However, that doesn't 
go far enough, I think. Is there any reason we can't do all of a table's 
indexes and non-FK constraints together? Will that affect anything other 
than PK and UNIQUE constraints, as NULL and CHECK constraints are 
included in table definitions?

cheers

andrew