Oracle will not index null values (with the exception of bitmap indices). .
This may mean that the optimiser will choose to do a full table scan rather
than use an apparently appropriate index. Conversely you may fnd that
indexes are far smaller and used more appropriately than if you filled the
field with a placeholder value (like 'UNKNOWN').
--
Niall Litchfield
Oracle DBA
Audit Commission UK
*****************************************
Please include version and platform
and SQL where applicable
It makes life easier and increases the
likelihood of a good answer
******************************************
"Steffen Ramlow" <s.ramlow_at_gmx.de> wrote in message
news:a2hake$112tge$1_at_ID-54600.news.dfncis.de...
> sample1:
>
> id col1 col2
> ---------------
> 1 v11 v12
>
>
> versus:
>
> sample2:
>
> id col1 col2
> ---------------
> 1 v11 null
> 1 null v12
>
>
> there maybe indexes on the tabel, at least in column id
>
> where r the problems in sample2?
>
>
Received on Tue Jan 22 2002 - 03:47:01 CST
