Re: Effect of number of extents on Oracle I/O performance

From: <>
Date: Fri, 13 Mar 2009 18:40:12 -0500
Message-ID: <>

Number of extents is irrelevant, especially with Locally Managed Tablespaces. Even in 8i I used to manage a database with huge interMedia Text indexed tables with out-of-line CLOBs. The tables and/or LOB segments had over 30,000 extents and we had subsecond response time to interMedia-type queries on the CLOBs. And that was on a Windows2k server.

With LMTs I haven't worried about extents or the "fragmentation" boogey-man in a decade.

Jack C. Applewhite - Database Administrator Austin I.S.D. - MIS Department
512.414.9715 (wk) / 512.935.5929 (pager)

Niall Litchfield <>  

Sent by: 03/13/2009 06:08 PM
Please respond to

Re: Effect of number of extents on Oracle I/O performance

I haven't seen what you describe since about 7.3.4, perhaps you could demonstrate what you mean so that we can try it out ourselves (I have a likely 11g candidate in mind).

On Fri, Mar 13, 2009 at 10:50 PM, Joel Wittenmyer <> wrote:

In Oracle 8 and 9 we saw that at 1000 extents performance began to drop off. At 2K extents it leapt, laughing maniacally off a cliff. I know that 10g is supposed to handle much more than that without a problem. Tens or hundreds of thousands perhaps? Does anyone have experience with just what the new threshold might be? Or is the architecture such now that it is no longer a consideration?

Thanks in Advance.

Joel Wittenmyer
Sr. Database Architect
Sr. Data Architect



Niall Litchfield
Oracle DBA

-- Received on Fri Mar 13 2009 - 18:40:12 CDT

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