Re: estimated of CLUSTERING_FACTOR

On Sep 5, 3:10 pm, Andrea <netsecur..._at_tiscali.it> wrote:
> On 5 Set, 13:58, sybrandb <sybra..._at_gmail.com> wrote:
>
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>
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> > On Sep 5, 1:09 pm, Andrea <netsecur..._at_tiscali.it> wrote:
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> > > Hi,
>
> > > i was reading some paper related on clustering factor, this column
> > > aimed to identified if the rows of a table are synchronized (ordered)
> > > with the index.
> > > If i don't mistake, the value of clustering_factor have to approached
> > > to number of blocks of the table and more far away from number of
> > > rows.
>
> > > So, if i have understood well, main indications on this column are:
>
> > > 1) if c factor is lower than blocks, maybe the table could have
> > > problems of fragmentation because of many DML statements (insert and
> > > delete)
>
> > > 2) if c factor is higher than blocks and it approach to num_rows, then
> > > the rows in the index are not ordered (not sync with the index).
>
> > > In first case: is SHRINK the table a method for resolve the problem?
> > > In second case: rebuild index resolve order of the rows ?
>
> > > Or, for both case the only best method is truncate and reinsert all
> > > rows?
>
> > > thanks for your advice and opinions.
> > > bye
> > > --
> > > Andrea
> > > ( a guy that tries to become to DBA)
>
> > The best method is to bother only when it will *resolve* anything.
> > Otherwise you are embarking on an exercise in futility and getting
> > paid for wasting your and your employers time.
>
> > --
>
> sorry but i discord with you, some crumbs of my FREE time i dedicated
> for learn and increase my competence.
> I think that one (but important) of DBA role is "also" do a proactive
> tuning of database.
> what is badly in this?
> if i search and engage to find possible bottleneck (leaf blocks,
> chained rows, objects fragmentation, waits, clustering factor, etc..)
> i could to avoid that this become to a problem (reactive).- Hide quoted text -
>
> - Show quoted text -

Please look up the word *resolve* in a dictionary. Your so-called 'proactive'  maintenance won't *resolve* anything, it will just waste resources, time and money.
It is the same issue as rebuilding indexes, rebuilding tables, defragmenting tablespaces etc: it just doesn't RESOLVE anything.

--
Sybrand Bakker
Senior Oracle DBA