On Friday, January 12, 2024, Sébastien TANIERE <seb.tani...@gmail.com> wrote:
> Hello, > in my company, some columns rarely used in a PG database 14.8 have been > set to NULL in order to save disk space (datecreation & acteurcreation in > following table) . > > create table example > ( > id varchar(25) not null, > datecreation timestamp(6), > acteurcreation varchar(50), > valeurunit smallint > ) > > I am wondering if it is really useful for every type of column. > Intuitively, i would say that it does not save space for fixed field > datecreation as it is a fixed size column. > > Do we save 8 bytes by timestamp column updated to NULL or not ? > > You probably should just measure it yourself. But yes, the representation of null in a tuple is the absence of data and a bit in the nulls bitmap. So there is overhead but also savings. The net effect is case specific. David J.
