> i have 11 columns total. column 1, 2, 3, 4, 5 and 6
> are NOT NULL. the rest can be null and, in the case
> of the imported data set, are null.
From:
http://www.postgresql.org/docs/8.1/interactive/sql-copy.html
COPY tablename ( column [, ...] )
FROM 'filename'
WITH NULL AS 'null string'
;