I was not clear enough, I agree about indexes and the foreign key requirements etc. I was more concerned about the check and not null constraints.
ORACLE-L_at_fatcity.com wrote:
>
> Hi, instead of talking about the performace overhead caused by enabled constraints i want to give you a simple example describing a worst scenario :
>
> Suppose to have a table A with a foreign Key on the field a1 pointing to the field b1 of table B
>
> Suppose to delete N record from the table B
> If the field a1 wasn't indexed you would wait for N full table scans on A
>
> Hope this helps
> Davide
>
> -----Original Message-----
> Sent: Wed, 06 Sep 2000 21:20:28 -0800
> To: ORACLE-L_at_fatcity.com
>
>
>
> What is the performance overhead (if any) on disabled constraints? My
> assumption is that Oracle will have to validate if a constraint is available
> and what the status is (ENABLED OR DISABLED). There should be a performance
> impact, with having
> constraints in ENABLED state
> Vs
> having constraints in DISABLED state
> Vs
> No constraints or constraints dropped.
>
> Any ideas or stats on this subject.
>
> Thanks
>
>
> Murali Vallath
>
>
>
>
> --
> Author:
> INET: MVallath_at_cs.com
>
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> --
> Author: Davide Bellesi
> INET: davide.bellesi_at_visto.com
>
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Received on Thu Sep 07 2000 - 10:58:12 CDT
