The second part on limiting the table size the the last 100 (still using my example here) rows can go something like this:
In the transaction group that adds rows to the FIFO two Expression Items are added. The first gets the oldest timestamp of the newest 100 rows:
Select min(t_stamp)
FROM (Select t_stamp
From FIFO1
Order by t_stamp desc
limit 100) as t_stamp
The second deletes everything older than the DateTime you just got, leaving 100 rows left in the table:
DELETE FROM FIFO1
WHERE t_stamp<'{[.]Oldest 100th Date}'
Borrowing Carl’s tagline: Hope this helps!
Regards,