Skewed columns

[malru]

In creating histograms,i read a term called "skewed data columns",Can anyone explain me what does it mean in detail with an example?

Thanks,
Malru

[davey23uk]

why dont you look it up in the docs, where it is explained?

tahiti.oracle.com

[malru]

It's explained in any doc,thats why i'm posting here.If you know,please explain.what exactly skewed column,means.

Thanks,
Malru

[Thomasps]

SQL> create table emp (ename varchar2(50), esex varchar2(10));

Table created.

SQL> insert into emp select object_name,'Male' from dba_objects;

9369 rows created.

SQL> commit;

Commit complete.

SQL> insert into emp select object_name,'Female' from dba_objects where rownum < 20;

19 rows created.

SQL> commit;

Commit complete.

SQL> select esex,count(*) from emp
  2  group by esex;

ESEX         COUNT(*)
---------- ----------
Female             19
Male             9369

Thats it.

[malru]

Thanks Thomasps,

Can you please explain this example because i didn't understand anything by this example?

[Thomasps]

Kindly read the oracle Docs or books from Tom Kyte and raise your dobts.

[malru]

I'm new to dba(self-learning),thats why i'm posting a lot here.

I read about skewed columns in Oralce docs only & searched in net also,but nowhere explained clearly what is skewed column,thats why i posted it hear,you've given an example,what is difficulty in explaining this,please explain it.

[Thomasps]

Ok. Read this.

http://asktom.oracle.com/pls/ask/f?p...A:707586567563

http://asktom.oracle.com/pls/ask/f?p...34807121420113

After reading explain me what is skewness? All the best