The PostgreSQL parser/producer has no native support for the SQL
"INHERITS" clause on table creation.
The attached zip file contains a patch, and copies of new/changed files,
to add INHERITS support for create table statements, with tests.
It turns out the parser grammar already understood INHERITS, but the
information was not being copied from the parse tree into the model. I
have added it to the "extra" field of the model, which was already being
used for the "temporary" table attribute.
Likewise, the producer was modified just enough to add the clause to
create table statements.
Note that this patch only implements partial support for inheritance,
because it makes no provision for adding/removing inheritance via ALTER
TABLE.
