New,
No guru here, but that is the way that I do it -
average row size vs estimated number of rows * fudge
factor of 30% plus a little room for underestimation.
Also, don't forget room for indexes.
I have found this method to be quite successful, since
the major hurdle is figuring out how many rows the
customers will have. Often, even they don't know for
sure, so you have to help them not hurt themselves by
being liberal in your space estimations.
Remember, if you overestimate, no one will know except
you and other dbas, since no one really cares after as
long as the system runs well in production. I have had
systems that were 50 megs sitting on 50 gig Veritas
clusters and everone was happy.
Underestimate space, though, and say hello to long
periods of data shuffling and constant firefighting.
As the old saying goes, "Goofups are forever."
hth,
Jack
- "CHAN Chor Ling Catherine (CSC)"
<clchan_at_nie.edu.sg> wrote:
> Hi Gurus,
>
> I found an article in metalink 105765.1 "How to
> Determine Approximate Hard
> Drive Space Needed for a Specific Table". The
> formula for disk space is
> simply multiplying the average row length (by
> analyzing the table) * the
> number of rows in the table. It's very different
> from Metalink 10640.1
> "Extent and Block Space Calculation and Usage in V7
> Database" where it takes
> the block header etc in considerations but of
> course, article 10640.1 is for
> Version 7.
>
> How do you gurus calculate table space in Version 8
> ? Please advise.
> Thanks.
>
> Regds,
> New Bee
>
>
> Doc ID </help/usaeng/Search/search.html> :
> Note:105765.1 Content
> Type: TEXT/PLAIN
> Specific Table Creation Date: 18-APR-2000
> Type: PROBLEM Last Revision Date: 26-DEC-2000
> Status: PUBLISHED
> Problem Description
> -------------------
> How can you determine how much disk space is needed
> for a table?
>
>
> Solution Description
> --------------------
> You can use SQL to determine how much space is
> needed for the table based
> upon the average row length.
>
> 1. compute statistics about this table:
>
> analyze CEUSER.CE_STATEMENT_LINES
> compute statistics;
>
> Now determine the average row length in bytes:
>
> select avg_row_len
> from dba_tables
> where table_name=' CE_STATEMENT_LINES';
>
> AVG_ROW_LEN
> ===============
> 98
>
>
> 2. Multiple the average row length in bytes by the
> number of rows you
> believe
> you will need:
>
> 98 (bytes) x 10000 records = 980000 bytes needed
>
> References
> ----------
> For more information on the ANALYSE command, you may
> wish to refer to:
>
> Oracle8 SQL Reference Release 8.0, Part No.A58225-01
>
> Also:
>
> Oracle8i SQL Reference Release 8.1.5, Part Number:
> A67779-01
> .
> --
> Please see the official ORACLE-L FAQ:
> http://www.orafaq.com
> --
> Author: CHAN Chor Ling Catherine (CSC)
> INET: clchan_at_nie.edu.sg
>
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Received on Wed Jul 10 2002 - 00:03:19 CDT
