One-field INDEX performance VS multiple fields index 
Author Message
 One-field INDEX performance VS multiple fields index
Hi.

 Is there any difference accessing Oracle table through
 index containing one field ( NUMBER(8)) only or through another
 index containing 5 or 6 fields ( including VARCHAR2 ) assuming
 that the number of selected rows is equal in both cases?

 I couldn't find any reference in Oracle documentation.

 Thanx. Michael.

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Wed, 18 Jun 1902 08:00:00 GMT
 One-field INDEX performance VS multiple fields index

Hi Michael,

The main difference is between unique and non-unique indexes. In your case I
would expect at least a bigger index in terms of blocks. There would be only
a disadvantage for the composite index when the B-tree would also get
higher.
My 2 cts vote is for the single column index.

Hth,

Sybrand Bakker, Oracle DBA

Quote:
> Hi.

>  Is there any difference accessing Oracle table through
>  index containing one field ( NUMBER(8)) only or through another
>  index containing 5 or 6 fields ( including VARCHAR2 ) assuming
>  that the number of selected rows is equal in both cases?

>  I couldn't find any reference in Oracle documentation.

>  Thanx. Michael.

> Sent via Deja.com http://www.deja.com/
> Share what you know. Learn what you don't.



Wed, 18 Jun 1902 08:00:00 GMT
 
 [ 2 post ] 

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