Thank you all, for your input.
Shiva
On 12/13/06, Charles Schultz <sacrophyte_at_gmail.com> wrote:
>
> *grin* Kinda. As far as I know, we do not gather any explicit stats on the
> system objects. But I have 40 objects from this query:
>
> 1 select TABLE_NAME,COLUMN_NAME,NUM_DISTINCT,NUM_NULLS,SAMPLE_SIZE
> 2 from dba_tab_cols where NUM_BUCKETS = 1 and HISTOGRAM = 'HEIGHT
> BALANCED'
> 3* and owner in ('SYS','SYSTEM')
>
> According to dba_histograms, they all have 1 row (as you mentioned). Not a
> big deal, just another quirkiness. A good thing the density is not "height
> balanced". =)
>
> On 12/13/06, Wolfgang Breitling <breitliw_at_centrexcc.com> wrote:
> >
> > Charles,
> >
> > I suspect you are referring to the case when you (or size skewonly)
> > collect a histogram requesting more than 1 bucket for a column with
> > num_distinct=1 (all rows have the same value for that column). You'll get a
> > histogram with one single row in dba_histograms - a 'size 1' "histogram" has
> > two rows in dba_histogram - which is really a frequency histogram (as it
> > should be when size > num_distinct) but is labelled a HB histogram in
> > dba_tab_columns.histogram.
> >
> > At 10:29 AM 12/13/2006, Charles Schultz wrote:
> >
> > Be careful with that. It is possible to have a height-balanced histogram
> > with one bucket, according some of those views. Granted, it is not really a
> > histogram at all, but the views have some funky logic in them.
> >
> > On 12/13/06, *Allen, Brandon* < Brandon.Allen_at_oneneck.com> wrote:
> > You are correct - 1 bucket = "no histogram". You can also query for
> > user_tab_columns.histogram = 'NONE' to confirm.
> >
> > Regards
> >
> > Wolfgang Breitling
> > Centrex Consulting Corporation
> > www.centrexcc.com
> > ______________________________________________________________________
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> >
>
>
>
> --
> Charles Schultz
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Received on Wed Dec 13 2006 - 13:08:47 CST
