Re: Why does a hard parse access data in the table in the query?

I've seen dynamic sampling consume up to 4 hrs "sampling" daga, 11.2.0.3 I believe

On Thu, Feb 7, 2019, 06:08 Norman Dunbar <oracle_at_dunbar-it.co.uk> wrote:

> On 07/02/2019 10:19, Norman Dunbar wrote:
> > I get the feeling I should know this, but it seems to have aged out of
> > the cache!
>
> Thanks to everyone who said "dynamic sampling" because that's what it
> appears to be. I haven't traced it yet, but:
>
> * It was a hard parse;
> * Optimizer_dynamic_Sampling = 2 (the default)
>
> Unfortunately, the stats on this database are gathered very frequently.
> So the default says to "gather dynamically when one or more of the
> tables has no stats" means that I shouldn't be seeing dynamic sampling.
>
> Maybe, because stats go stale pretty quickly on some tables, it's taking
> "stale" to mean "none"? I wonder.
>
> Anyway, thanks again, you have been most helpful and hopefully, this
> won't age out of cache too soon! :o)
>
>
> Cheers,
> Norm.
>
>
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> Norman Dunbar
> Dunbar IT Consultants Ltd
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>

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