INSERT INTO ... ON DUPLICATE KEY UPDATE - mysql

Question

i want to log timestamp, parameter_id and value into my db, using the timestamp and the parameter_id as the primary, unique key.
data_togo, CREATE TABLE 'data_togo' (
'id_para' int(10) unsigned NOT NULL DEFAULT '0',
't_ns' bigint(20) unsigned NOT NULL DEFAULT '0',
'id_inst' smallint(6) NOT NULL DEFAULT '1',
'value' varchar(255) NOT NULL DEFAULT '',
'isanchor' tinyint(4) unsigned NOT NULL DEFAULT '0',
PRIMARY KEY ('t_ns','id_para')
) ENGINE=InnoDB DEFAULT CHARSET=utf8
However in a very rare condition the case can happen where there are duplicate primary keys with different values.
INSERT INTO data_togo (id_para, t_ns, id_inst, value, is_anchor) VALUES ...
Is it possible to keep both rows and update the second timestamp (nanoseconds, so that would not matter) to +1?
EDIT: Problem: currently there is a bug where i get the data from, the timestamp is rounded to milliseconds with microseconds resolution and then brought into nanoseconds format. hence, if it goes badly both the DIFFERENT timestamps are rounded to the same value, which leads to a duplicate primary key.

Answer 1

I've found a solution that works for two times the same timestamp:
Transfer the whole thing into a stored procedure
If the row exists, insert it with the following statement:
INSERT INTO edl_dw.data_togo (id_para, t_ns, id_inst, value, isanchor)
VALUES(#id_para, #t_ns, #id_inst, #value, #anchor)
ON DUPLICATE KEY UPDATE t_ns= #t_ns-1;
Then insert another row into the table with the same content, but with insert ignore
INSERT IGNORE edl_dw.data_togo (id_para, t_ns, id_inst, value, isanchor)
VALUES(#id_para, #t_ns, #id_inst, #value, #anchor);
If the row already existed, the old row timestamp will be set 1 ns back, but the content is kept. Then the new row gets inserted after that.
If the row didn't exist, the row get's inserted in the first statement, and the second insert gets ignored because the primary key already exists.