Matt Andrews <mattandrews@massey.com.au> writes:
> Incidentally, I have become interested in the pg_node_tree type. I can't
> find much info on it. Would that be in the source? What would be the first
> steps for writing an extension for this sort of thing?
pg_node_tree is just a serialization of the tree-of-Node-structs
representation used inside the server. See
src/include/nodes/primnodes.h and adjacent files for Node definitions.
The actual serialization code is in src/backend/nodes/outfuncs.c
and adjacent files.
(Beware, however, that there's proposals floating around to change
the serialization format.)
regards, tom lane