Re: COPY table_name (single_column) FROM 'iso-8859-1.txt' DELIMITER E'\n'

What about:

   COPY ... FROM ... WITH PATTERN 'regexp_pattern'

Where the columns would be matched with the capture groups.

This could handle the quite common case of varying white-space as column separators:

   COPY log (col1, col2, col3) FROM 'log.txt' WITH PATTERN '^(\S+)\s+(\S+)\s+(\S+)$'

This could also handle $SUBJECT:

   COPY table_name (single_column) FROM 'unknown.txt' WITH PATTERN '^(.*)$';

And lots of other more complex use-cases.

/Joel