Re: index selectivity

From: <michael_bialik_at_my-deja.com>
Date: Wed, 20 Oct 1999 20:21:50 GMT
Message-ID: <7ul88f$mo1$1@nnrp1.deja.com>

Hi.

You are correct assuming the usage of constants. If you are using bind variables - optimizer still assumes even distribution and does not use indexes.

Michael.

In article <380C5B43.1C98_at_yahoo.com>,
connor_mcdonald_at_yahoo.com wrote:
> The optimiser assumes an even distribution. But you can create
> histograms on columns during analyze (see the doco for ANALYZE) which
> then stores the distribution of the data. The optimiser can then use
> this to make more informed decisions on whether to use the index or
not.
>
> HTH
> --
> ===========================================
> Connor McDonald
> "These views mine, no-one elses etc etc"
> connor_mcdonald_at_yahoo.com
>
> "Some days you're the pigeon, and some days you're the statue."
>

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Before you buy. Received on Wed Oct 20 1999 - 15:21:50 CDT