How much memory will be occupied by a null value in a DB?

Question

I was wondering how much memory does a null value occupy in a database can anyone answer clearly?

Depends on the database - IE SQL Server: http://weblogs.sqlteam.com/mladenp/archive/2007/09/06/How_does_SQL_Server_really_store_NULL-s.aspx — OMG Ponies, May 03 '11 at 04:42
NULL is not a value - it's the **absence** of a value. Shouldn't be occupying any space at all (since there is nothing to store, really....) — marc_s, May 03 '11 at 04:42
**Memory**? Don't you confuse it with disk storage? And what dbms do you use? — zerkms, May 03 '11 at 04:42
I highly suggest reasking this question on http://dba.stackexchange.com — jcolebrand, May 03 '11 at 04:47
@zerkms Trust me, too many people confuse memory with disk usage. — BoltClock, May 03 '11 at 04:49
I wonder if CJ Date dies a little inside every time a question like this gets asked. A NULL question and storage question in one — Conrad Frix, May 03 '11 at 04:51
@Conard Frix No theoritically marc_s may be wrong but practically he is right how database knows whether an entry is null it should have something like flag to say its a null. — satheesh.droid, May 03 '11 at 04:51

score 5 · Answer 1 · answered May 03 '11 at 04:57

How much space it takes up depends on what the column is defined to be and on the storage engine being used. Some data types take a fixed amount of space regardless of the data stored. There is a small space penalty for declaring a column to accept NULL. Details can be found in this general discussion in the manual and more in the docs about each storage engine.

How much memory will be occupied by a null value in a DB?

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