Re: primary key width limit, why, can it be overriden

A copy of this was sent to Furkan Khan <khanf_at_home.com> (if that email address didn't require changing) On Thu, 24 Jun 1999 22:33:23 GMT, you wrote:

>Folks, does anyone know why there is a limit
>on how wide the primary key (including any
>candidate keys) can be.
>
>
>Does any one know:
>a. the reason for this limit.

speed, efficiency, reasonable limits....

>b. what is the limit on Sun Solaris

depends on the blocksize of the database. the max size of an index is a little less then 1/2 the size (say about 40%) of the block OR 16 columns in o7, 32 columns in o8 -- whichever comes first

>c. How to override this limit

use a larger block size.

Beware tho, a primary key that is more then a couple dozen bytes is a *bad* idea. keys should be 'reasonably' small. If I had a primary/candidate key with 32 columns or that was 1,000 bytes wide -- i would be worried about my model...

>
>Thanks in advance.
>Furkan Khan

--
See http://govt.us.oracle.com/~tkyte/ for my columns 'Digging-in to Oracle8i'... Current article is "Part I of V, Autonomous Transactions" updated June 21'st  

Thomas Kyte                   tkyte_at_us.oracle.com
Oracle Service Industries     Reston, VA   USA

Opinions are mine and do not necessarily reflect those of Oracle Corporation Received on Fri Jun 25 1999 - 06:19:15 CDT