Re: Table growth - disk sizing
- From: Ranko Mosic <ranko.mosic@xxxxxxxxx>
- To: Christian.Antognini@xxxxxxxxxxxx
- Date: Fri, 26 Aug 2005 12:00:28 -0400
Back to the initial question ( requirement priority keeps changing -
now table growth is priority again):
I need to estimate table growth. Database is still not in production
so I can't track growth and predict table size in conventional way.
I am thinking on modeling table growth based on known number of transactions per
year; finding how much disk space each transaction takes in each
table; then multiplying by number of transactions per year;
theoreticaly it should work - the only problem I see is: how to figure
out exact disk space used per transaction .
Convoluted ? Impossible ?
Please advise.
On 8/25/05, Christian Antognini <Christian.Antognini@xxxxxxxxxxxx> wrote:
> >-----Original Message-----
> >From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx]
> >On Behalf Of Thomas Day
> >Sent: 25 August 2005 19:03
> >To: Oracle-L
> >Subject: Re: Table growth - disk sizing
> >
> >Would you care to explain?
>
> Tom
>
> In a "regular" index the data is stored in ascending order (e.g. ..., 11, 12,
> 13, 14, 15, 16, ...). If you create an index on a column where the data is
> inserted in "progression" (e.g. timestamp of the transaction or value
> generated by a sequence), it's very likely, for concurrent transactions, to
> modify the right-most leaf block. Of course this situation will result in
> waits.
>
> Now, if you store the data in descending order (e.g. ..., 16, 15, 14, 13, 12,
> 11, ...) you will simply move the contention to the left-most leaf block,
> i.e. it's not reduced.
>
> A possible solution for such a contention problem, it's to store the data in
> reserve order (e.g. ..., 11, 21, 31, 41, 51, 61, ...). With this method the
> transaction are well spread over "all" leaf blocks. Of course they are
> drawbacks as well. One of the most important is the poor support of range
> scans (the data is in the wrong order...).
>
> HTH
> Chris
>
>
> New Features Oracle Database 10g Release 2 seminars @ www.trivadis.com
> Italiano: Lugano (24-Nov)
> Français: Genève (17-Nov)
> Deutsch: Zürich (11-Oct), Hamburg (13-Oct), München (20-Oct), Basel (25-Oct),
> Frankfurt (27-Oct), Bern (8-Nov), Düsseldorf (23-Nov), Stuttgart
> (13-Dec)
> --
> //www.freelists.org/webpage/oracle-l
>
--
//www.freelists.org/webpage/oracle-l
Other related posts:
