If you have an indexed DATE or DATETIME field in MySQL, you really want to use the date and time functions to do your grouping. This seems to add unnecessary c

If you have an indexed DATE or DATETIME field in MySQL, you really want to use the date and time functions to do your grouping. This seems to add unnecessary complexity and overhead. There is already plenty of build-in abstraction for date manipulation in MySQL, and you really don't want to be dependent on any stored procedure or function if you can avoid it. http://dev.mysql.com/doc/refman/5.5/en/date-and-time-functions.html http://dev.mysql.com/doc/refman/5.5/en/date-and-time-functio... I can't speak for postgres though. It might be different.