27.02.2018 06:42, hugo.larson@... [firebird-support] wrote:

>
> Does null values take up disk space?

Yes, but much less than the declared column size.

> If I have a table with 4 VARCHAR columns and I add 4 more does the table
> need double space even if the new columns are null?

Already existing records will not be extended at all, the occupied space
will remain the same. New record versions may slightly increase in size,
but not double.


Dmitry