You have a large dataset that contains more than 1 million rows.

We have to separate date & time tables. Also, we don’t need to put the time into the date table, because the time is repeated every day.

Split your DateTime column into a separate date & time columns in fact table, so that you can join the date to the date table & the time to the time table. The time need to be converted to the nearest round minute or second so that every time in your data corresponds to a row in your time table.