Skewed columns

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

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

tahiti.oracle.com

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

Thanks,
Malru

Code:

---

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.

Thanks Thomasps,

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

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

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.

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