Re: conditional unique index to restrict duplicates of a particular set

Would you please elaborate why an INSERT/UPDATE trigger using a non-unique index on those 4 columns would not scale? The trigger would do an index lookup using the 4 columns when the set of values passed is expected to be unique and raise an error if there exists such set. This method would be clean, and the index could be used by other queries.

Cheers — Carlos

On May 7, 2014, at 9:50 AM, Mohamed Houri <mohamed.houri_at_gmail.com> wrote:

> I am wondering how you will be able to enforce uniqueness via a trigger in a multi-user concurent application? It will not scale. You need either to use your unique function based index or, if in 11gR1 and up create a virtual column and place a unique constraint (unique index) on this virtual column
>
> Best regards
> Mohamed Houri
>
>
> 2014-05-07 15:13 GMT+02:00 Fergal Taheny <ftaheny_at_gmail.com>:
> Hi Carlos,
>
> Won't you face a mutating table error if you try to use a trigger for this.
>
> Regards,
> Fergal
>
>
>
>
> --
> Bien Respectueusement
> Mohamed Houri

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