Re: Do columns with Null data take up space?

"DA Morgan" <damorgan_at_x.washington.edu> wrote in message news:41e554df$1_1_at_127.0.0.1...
> Doug wrote:
>
> > If I create a table with 250 columns, and only fill 8, do the other
> > columns take up space? (My user wants to log tests. There can be as
> > many at 250 tests in a set, but normally only about 8. My user wants
> > one record per set so he can run some third party analytical software
> > against the test results.) Is Oracle 8i smart enough to compress the
> > null values down so they don't take up space if they are unused?
>
> There is nothing to compress. Null is null. There may be one or two byte
> overhead but of bigger concern is a table with 250 columns. That has all
> of the appearance of a very bad design.
> --
> Daniel A. Morgan
> University of Washington
> damorgan_at_x.washington.edu
> (replace 'x' with 'u' to respond)

http://download-west.oracle.com/docs/cd/B10501_01/server.920/a96524/c11schem.htm#2715

Quote from the concepts manual ..
To conserve space, a null in a column only stores the column length (zero). Oracle does not store data for the null column. Also, for trailing null columns, Oracle does not even store the column length. Received on Wed Jan 12 2005 - 17:51:46 CST