Bright ideas required for drop column...

Does anyone know how I should modify MergeAttributes to support dropped
columns?

If the parent column is dropped, should I perhaps just instead of going:

def = makeNode(ColumnDef);

I could go something like:

def = makeNullNode(); (or whatever the correct function is)

Or should I modify or remove this sort of thing?:

inhSchema = lappend(inhSchema, def);

This is to stop a new child table from inheriting dropped columns by
default...

Also, the last thing after that on my checklist is fixing these two:

CREATE CONSTRAINT TRIGGER
ALTER TABLE / ADD FOREIGN KEY

Where should I do the check for these? For the alter table case, I can
check that the foreign keys and primary keys actually exist in
createForeignKeyConstraint, but that means that it's already done the table
scan to validate the foreign key.

And I can't for the life of me actually find where a CREATE CONSTRAINT
TRIGGER statement is processed...

Chris