Bug in information_schema: FK constraint is defined as against referenced table only

Folks,

I've been trying to extract some information about referencing tables
from information_schema, and discovering that it isn't there.

For example, take the following FK, from table Errors to table Files:

CONSTRAINT errors_file_fkey FOREIGN KEY (file)
REFERENCES files (id) MATCH SIMPLE
ON UPDATE CASCADE ON DELETE CASCADE

What's listed in referential_constraints is:

constraint_catalog | constraint_schema | constraint_name |
unique_constraint_catalog | unique_constraint_schema |
unique_constraint_name | match_option | update_rule | delete_rule
apple3 | public | errors_file_fkey | apple3
| public | files_pkey |
NONE | CASCADE | CASCADE

Ok, there's some useful information about the *referenced* table,
including its unique constraint. Doesn't tell us anything about the
*referencing* table, though.

Let's look up the data on errors_file_fkey constraint in
constrain_column_usage:

table_catalog | table_schema | table_name | column_name |
constraint_catalog | constraint_schema | constraint_name
apple3 | public | files | id | apple3
| public | errors_file_fkey

Huh? This shows errors_file_fkey constraint defined on the *referenced*
table only.

constraint_table_usage has this:

table_catalog | table_schema | table_name | constraint_catalog |
constraint_schema | constraint_name
---------------+--------------+------------+--------------------+-------------------+------------------
apple3 | public | files | apple3 |
public | errors_file_fkey

By information_schema, you wouldn't have any idea that errors_file_fkey
is defined on the table Errors, let alone what columns it's defined
against.

Poke around; you'll discover that there is no information about
referencing tables in information_schema at all.

This has got to be a bug, even if the SQL standard can be read to
support it.

I'm happy to write some code to fix it, if we can agree what these views
should show. I think constraint_column_usage and constraint_table_usage
should be showing the data of both the referenced and referencing tables.

--Josh Berkus