Posted by vikram.mankar on 02/07/07 14:48

Thanks Erland - i noticed the performance is much better with WHERE
NOT EXISTS... and the SQL Job completes much more cleanly.


On Feb 7, 3:20 am, Erland Sommarskog <esq...@sommarskog.se> wrote:
> (vikram.man...@gmail.com) writes:
> > I'll give it a shot. Is it generally more efficient to check for
> > duplicates through T-SQLlike with WHERE NOT EXISTS? or use
> > constraints on the table? I realize the latter is a little painful as
> > it clogs the error logs for the job history.
>
> If you want to prevent duplicates at all, you should use constraints.
> And then you may use WHERE NOT EXISTS to avoid the errors to happen.
> Note that if you only use WHERE NOT EXISTS, but does not have any index
> at all, performance will be awful.
>
> As for that log table, I would not put any constraints on that table
> that prevents duplicates, nor any WHERE NOT EXISTS. It seems to me that
> it may be better to permitt the application to log what it logs and
> weed out duplicates later.
>
> --
> Erland Sommarskog,SQLServer MVP, esq...@sommarskog.se
>
> Books Online forSQLServer 2005 athttp://www.microsoft.com/technet/prodtechnol/sql/2005/downloads/books...
> Books Online forSQLServer 2000 athttp://www.microsoft.com/sql/prodinfo/previousversions/books.mspx

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