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Oracle Magazine excels itself

From: Jonathan Lewis <>
Date: Fri, 28 Feb 2003 23:29:36 -0800
Message-ID: <>

I think it was only a few weeks ago that I posted a list of errors in an article about statspack that Oracle Magazine published in January.

You may be interested to see that another reader sent a letter to the editor about the same article, which has been published, with a response, in the March issue.


    I found an error in "Advanced Tuning with Statspack" in your     January/February 2003 issue. Rich Niemiec writes that in     the event of a wait on a segment header to increase the     Freelist groups. Freelist groups only apply to Oracle9i RAC     systems, and have nothing to do buffer busy waits on     non-RAC systems.

<<end quote>>

<< my comment>>

It is, of course, unfortunate that this 'correction' is actually wrong. Although the manuals have persistently stated, until very recently, that freelist groups were relevant only to OPS, they have been effective in single instance Oracle for a long time - possibly as far back as 7.2.3

<<end of my comment>>

<<Rich Niemiec's reply>>

    Freelist groups do, in fact, have some benefits apart from     Oracle9i RAC. MetaLink says that Freelist groups can     have a positive impact in an exclusive environment     (non-RAC) by helping reduce contention on the segment     header. However, I should point out that segment header     block contention can be addressed without multiple Freelist     groups, for example, by increasing the pctfree/pctused gap     or by partitioning the segment.

<<end of reply>>

<<My comments>>

Surely the point of a 'readers comments' section is to get feedback from the readers, add value to the article by including readers' experiences or extra observations, allow expression of readers' attitudes and feelings (without an aggressive editorial response), and, if an actual error does get noted, allow a correction to be published.

So why publish this erroneous correction ? It did not add value to the article, it didn't even expose the need for clarification of a point. It merely elicited a repetition of some material that had already been stated in the article (which originally said: "... If this is the case, increase the freelist groups or increase the pctused to pctfree gap"...) plus the claim that the author had to be right because the comment was taken from Metalink.

It would, quite arguably, have been valid to reply with something like: "Your comments do, indeed reflect a well-known, and often documented, misconception about freelist groups. However, the behaviour changed in Oracle 7.X.X, and single-instance Oracle will take advantage of multiple free list groups. Be careful, however, that you set FREELISTS and FREELIST GROUPS to relatively co-prime numbers, or you will lose some of the benefits etc....."

So what has the dialogue achieved:

  1. It hasn't improved the knowledge of the readers.
  2. It has told readers that they had better not write in if they think that there is an error in one of the articles unless they want to run the risk of looking stupid in public.
  3. It has given Rich Niemiec the chance to say "I'm right, you're wrong - yah, boo, sucks".

I'm not impressed..


Jonathan Lewis

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Received on Sat Mar 01 2003 - 01:29:36 CST

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