In my MySQL DB I have one field called `html_contents` that contains all the html to be shown in a webpage. Obviously the html could be huge, and certaintly bigger than 64KB, therefore I decided to use `LONGTEXT` rather than `VARCHAR`.

When the field is not set or left empty would you say it is better (alias more efficient for the DB) to set it to NULL or to empty string?

I read this: https://dba.stackexchange.com/questions/59/when-to-use-null-and-when-to-use-an-empty-string but it talks about empty strings in general (probably small strings and not `LONGTEXT`).

I was wondering if with `LONGTEXT` is a different story, whether it saves a lot of space or execution time to use `NULL` instead of leaving empty `LONGTEXT` around.