[web2py] Problem with Oracle access and web2py database administration

[tomt]

I recently tried to access some legacy tables in an Oracle database
with web2py. The connection string and model I generated in db.py
allows successful connection and queries from the command line are
successful, when I try to use the web2py database administration
function I get the following error:

Invalid Query ORA-00907: missing right parenthesis

The connection string is:
db = DAL('oracle://username:password@database')

And a typical table in the model looks like this:
db.define_table('tablename',
     Field('column1','integer'),
     Field('column2','string'),
     Field('column3','integer'),
     Field('column4','integer'),
     primarykey=['column1'],
     migrate=False
)
(The first column is unique but it is NOT autoincrementing)

I don't expect to be able to edit these tables with the dbadmin tool,
but I thought I would be able to view the rows. (I have had success
with legacy tables in mysql)

Perhaps there is something unusual about my Oracle tables, but I'm not
sure where to start debugging this problem.  Any suggestions?

Thanks, -Tom