sql.py: put(): When encountering a DuplicateKeyException, use dict_subset_right_join to fill in explicit NULL values for columns which don't have data. This causes the database to use the UNIQUE constraint's index to look up the record, instead of relying on individual column indexes for the columns that did have data, which may or may not be available.
sql.py: put(): When encountering a DuplicateKeyException, use dict_subset_right_join to fill in explicit NULL values for columns which don't have data. This causes the database to use the UNIQUE constraint's index to look up the record, instead of relying on individual column indexes for the columns that did have data, which may or may not be available.