In order to do it this way we'd need to make this new field an index. The posts table already has 9 different indexes. Indexes are great for selects but too many of them and any inserts or updates start to really slow down. This would mainly affect the addpost.pl script which already has to work very hard with all the queries and updates it does. For this reason I think it would be best to keep it in a different table so it only gets hit when clicking on the notify moderator icon.