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Re: Perf Tuning

From: John Russell <netnews3_at_johnrussell.mailshell.com>
Date: Tue, 14 May 2002 04:53:32 GMT
Message-ID: <bi51eucstqigsdq8n27qfejod43jsukt23@4ax.com>


On Mon, 13 May 2002 23:30:23 GMT, "Alex Ivascu" <alex_at_ivascu.com> wrote:
>Ouch!
>
>I did a simple test w/ 150K rows. It does seem to make a difference (small
>one), but it does. Wonder why?

Are the numbers the same for both COUNT() results? I thought COUNT(*) counted nulls too, while COUNT(column_name) omitted nulls.

http://otn.oracle.com/docs/products/oracle8i/doc_library/817_doc/server.817/a85397/function.htm#82712

Searching for "count(*) and nulls" also turns up some discussion of performance differences depending on whether bitmap indexes are used or not.

John

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Received on Mon May 13 2002 - 23:53:32 CDT

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