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Re: Count(*) Versus Count(1)

From: William Robertson <williamr2019_at_googlemail.com>
Date: 3 May 2007 05:29:26 -0700
Message-ID: <1178195366.203818.320690@l77g2000hsb.googlegroups.com>


On May 3, 7:02 am, "Vladimir M. Zakharychev" <vladimir.zakharyc..._at_gmail.com> wrote:
> On May 3, 9:21 am, Priya <supriyarsh..._at_gmail.com> wrote:
>
> > Hi,
>
> > I Read on Many sites about Count (*) and Count(1). But there are
> > conflicts in the documents.
> > Some where it has been specified like count (*) gives better
> > performance and somewhere it is like Count (1) gives better
> > performance.
>
> > Can anybody please help me to understand how it works and which one is
> > better for performance?
>
> > Any help would be appreciated.
>
> > Thanks
>
> http://www.oracledba.co.uk/tips/count_speed.htm, Google archives,
> numerous other places. To sum up: there are no significant differences
> in performance between count(*) and count(1) beyond usual experiment
> error, and Oracle does exactly the same amount of work for both.
>
> Regards,
> Vladimir M. Zakharychev
> N-Networks, makers of Dynamic PSP(tm)
> http://www.dynamicpsp.com

Actually slightly more work for COUNT(1), since the optimizer has to substitute COUNT(*) internally.

If any document recommends something as idiotic as using COUNT(1) instead of COUNT(*) I think you can safely disregard any other advice in that document. Received on Thu May 03 2007 - 07:29:26 CDT

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