Size taken by NULL

Question

Size taken by NULL

VastSQL

SSC-Dedicated

Points: 36097
More actions
September 25, 2018 at 6:44 am

#364210

Hi Experts,
We have a column with 136 columns and out of which 21 columns are NULL for the total 65000 rows.
How to find the size taken by these columns which have nothing?

Viewing 5 posts - 1 through 4 (of 4 total)

You must be logged in to reply to this topic. Login to reply

Joe Torre SSChampion Points: 10248 More actions · Answer 1

In google I typed in:
"sql server how much space does a null take up", This was the top result:
https://stackoverflow.com/questions/3731172/how-much-size-null-value-takes-in-sql-server

Steve Jones - SSC Editor SSC Guru Points: 736252 More actions · Answer 2

To repeat the answers, same size space for fixed size fields, 0 for variable fields. There's a null bitmap

VastSQL SSC-Dedicated Points: 36097 More actions · Answer 3

Steve Jones - SSC Editor - Wednesday, September 26, 2018 12:29 PM
To repeat the answers, same size space for fixed size fields, 0 for variable fields. There's a null bitmap

Thanks Steve. What about the overhead of 1 byte , i read if we didnt use sparse it takes up some space.

Steve Jones - SSC Editor SSC Guru Points: 736252 More actions · Answer 4

There is a good explanation here. It's not 0 byte for nulls: https://stackoverflow.com/questions/3793022/how-do-you-get-to-limits-of-8060-bytes-per-row-and-8000-per-varchar-nvarchar/3793265#3793265

The sparse column thing is for fixed width fields, like int, tinyint,etc