RE: RE: Tablespace management.

Wolfgang,

I agree. I wasn't arguing a point, but merely pointing out a possible source of the information you had requested.

Have a weekend! :)

Rich

Rich Jesse                        System/Database Administrator
rich.jesse_at_qtiworld.com           Quad/Tech International, Sussex, WI USA

> -----Original Message-----
> From: Wolfgang Breitling [mailto:breitliw_at_centrexcc.com]
> Sent: Friday, May 30, 2003 4:00 PM
> To: Multiple recipients of list ORACLE-L
> Subject: RE: RE: Tablespace management.
>
>
> To quote the paper:
>
> "Oracle supports an unlimited number of extents in a segment. The
> performance for DML operations is largely independent
> of the number of extents in the segment. However, certain DDL
> operations
> such as dropping and truncating of segments are
> sensitive to the number of extents. Performance measures for these
> operations have shown that a few thousand extents can be
> supported by Oracle without a significant impact on performance. A
> reasonable maximum has been determined to be 4096.
> The goal of our recommended algorithm is to keep the number
> of extents
> below 1024 which is well within the range that
> Oracle can efficiently handle. When a segment reaches 1024
> extents it is a
> candidate to be moved to the next larger extent
> size tablespace. The segment does not necessarily have to be moved
> immediately or at all. The segment may be near its peak
> steady state size, in which case even if it has a few
> thousand extents, it
> should be left where it is. It is only the segments which
> are growing that have to be targeted and potentially moved to
> tablespaces
> with larger extents."
>
> A few comments:
>
> - This was written in the days of DMTs, so not everything
> that is said
> applies to LMTs. The nr of extent stuff certainly does not.
>
> - Event within the confines of DMTs it clearly states that
> only drop and
> truncate are sensitive to the nr of extents (because of the
> necessary DML
> to FET$ and UET$).
>
> - And even then, 1024 is not really a limit, just a
> recommended comfort
> level: "The goal of our recommended algorithm is to keep the
> number of
> extents below 1024 which is well within
> the range that Oracle can efficiently handle" and "The
> segment does not
> necessarily have to be moved immediately or at all"
>
> At 11:59 AM 5/30/2003 -0800, you wrote:
> >The "How To Stop Defragmenting..." paper says it in section 2.1.4.
> >
> >
> >Rich
> >
> >Rich Jesse System/Database Administrator
> >rich.jesse_at_qtiworld.com Quad/Tech International,
> Sussex, WI USA
>
> Wolfgang Breitling
>

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Author: Jesse, Rich
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