RE: gather stats

From: Ahmed Aangour <ahmed.aangour_at_gmail.com>
Date: Mon, 9 Nov 2015 19:16:44 +0100
Message-ID: <CAPK9FYEXSHTTdMcpi+Lw6gjtYiAKreRHO_=aWq-=DXef6dw3PA_at_mail.gmail.com>

The potential issue does not concern frequency histograms but rather Height Balanced histograms. The fact that some values can be seen as popular one day and not popular another day can constitute a cause of instability Le 9 nov. 2015 7:07 PM, "Matt Adams" <MAdams_at_troversolutions.com> a écrit :

> I can understand not gathering histograms across all columns due to the
> potential time it would take to do so. Is there any other technical reason
> not to..(perhaps some issue with the optimizer I'm not currently aware of)?
>
> I routinely gather histogram information for all INDEXED columns.
>
> Matt Adams
>
> -----Original Message-----
> From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org]
> On Behalf Of Wolfgang Breitling
> Sent: Monday, November 09, 2015 12:13 PM
> To: kp0773_at_gmail.com
> Cc: Oracle-L_at_freelists.org
> Subject: Re: gather stats
>
> Use auto_sample_size and refrain from gathering histograms on all columns
> ( method_opt 'for all columns size 1')
>
> Sent from my iPhone. Typing errors may have occurred.
>
> > On Nov 9, 2015, at 10:01, K R <kp0773_at_gmail.com> wrote:
> >
> > All,
> >
> > What is the recommended way of gathering stats on 11gR2 database (
> 2.5 TB) . If i keep estimate percent 10,15 then some of the table are
> taking hours and hours .
> > Please let me know .
> >
> > Thanks in advance.
> >
> > Kart.
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Received on Mon Nov 09 2015 - 19:16:44 CET