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Re: many "or" operation make system choose incorrect index

Posted by lsllcm on 11/28/07 15:39

On Nov 28, 6:27 am, Erland Sommarskog <esq...@sommarskog.se> wrote:
> lsllcm (lsl...@gmail.com) writes:
> > Hi Gert-Jan/Erland Sommarskog,
>
> > Thanks for your input.
>
> > The whole sql is very long.
> >...
> > yes, I have reduced the OR number to 62, the optimizer chooses
> > different index plan. When there are 63 OR operators, the optimizer
> > chooses the partial index scan
>
> > Seek predicts : Prefix: [sacco].[dbo].[BCHCKBOX].SERV_PROV_CODE =
> > 'SACCO'
>
> Seeing you SQL, performance appears to be your smallest problem. That
> code must be about unmaintainable. I would get those values in to a
> table. That may or may not help you to the best performance, but at
> least you will be better equipped to battle the problems.
>
> > Where can I found the document of 63 is the value?
>
> I doubt that it's documented. I found it on my own by testing.
>
> > Because multiple client access the site, I don't know how to use
> > temporary table to do it, could you give me one example?
>
> I don't see why the multiple clients would cause the problem. But since
> I don't where you get all these values from or much at all about
> your system, I cannot any examples.
>
> Did you say which version of SQL Server you are using`?
>
> --
> Erland Sommarskog, SQL Server MVP, esq...@sommarskog.se
>
> Books Online for SQL Server 2005 athttp://www.microsoft.com/technet/prodtechnol/sql/2005/downloads/books...
> Books Online for SQL Server 2000 athttp://www.microsoft.com/sql/prodinfo/previousversions/books.mspx

Hi Erland Sommarskog,

Could you provide the test step of 63 value

Thanks

 

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