[web2py] migrating to postgres error

[Plumo]

I have an app working with sqlite. I tried changing to postgres and get 
this error:

<class 'psycopg2.ProgrammingError'>(syntax error at or near "user" LINE 3: 
user INTEGER REFERENCES auth_user(id) ON DELETE CASCADE, ^ )

This is the relevant table:

db.define_table('purchase',
    Field 
<https://web2py_admin.baron.webfactional.com/examples/global/vars/Field>('user',
 db.auth_user),
    Field 
<https://web2py_admin.baron.webfactional.com/examples/global/vars/Field>('database',
 db.database),
    Field 
<https://web2py_admin.baron.webfactional.com/examples/global/vars/Field>('txn_id',
 unique=True),
    Field 
<https://web2py_admin.baron.webfactional.com/examples/global/vars/Field>('price',
 'decimal(8,2)', required=True, requires=IS_DECIMAL_IN_RANGE 
<https://web2py_admin.baron.webfactional.com/examples/global/vars/IS_DECIMAL_IN_RANGE>(0,
 1e100)),
    Field 
<https://web2py_admin.baron.webfactional.com/examples/global/vars/Field>('created',
 'datetime', compute=now),
)


Any ideas? The auth_user table is the default.

Richard