Re: Periodic Stats Collection -- CBO Stats Myth?
- From: "Sriram Kumar" <k.sriramkumar@xxxxxxxxx>
- To: "Wolfgang Breitling" <breitliw@xxxxxxxxxxxxx>
- Date: Fri, 3 Oct 2008 16:10:29 -0400
Hi Wolfgang,
Thans for your valuable inputs.
if the min and max are out of the sample data then they are not real end
point values. Going back to original quetsion, does this mean that we do not
need to recollect/ re adjust ( using PREPARE_COLUMN_VALUES)?. I agree that
May be we cannot completely get away with outdated end point values but the
periodicity of collection/adjustment can be quite less ( say once in a
month).
Best Regards
Sriram Kumar
On Fri, Oct 3, 2008 at 4:00 PM, Wolfgang Breitling
<breitliw@xxxxxxxxxxxxx>wrote:
> gather_table_stats with an estimate_percent of less than 100 uses the
> sample option of the from clause, e.g. select ... from tbl sample(10) and
> determine the min and max values for columns based on the values in the rows
> returned by the sample.
>
> At 12:50 PM 10/3/2008, Sriram Kumar wrote:
>
>> Hi Tim,
>>
>> Thanks for your inputs. Appriciate your inputs.
>>
>> I had one more question. If we are performing sampling ( lets say 10
>> percent), how does the stats gatherer estimate the high value especially for
>> date columns?.
>>
>> Best Regards
>>
>> Sriram Kumar
>>
>>
> Regards
>
> Wolfgang Breitling
> Centrex Consulting Corporation
> www.centrexcc.com
>
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