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Thread: indexes love big blocks

  1. #1
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    Question indexes love big blocks

    I was wondering if I can get people to have a civilized discusion on this article, how silly of me. But let's try anyway. Has anyone looked at the TPC white papers in detail? What do you think of the original article or the supporting links?

    Originally posted by TomKyte
    ...

    Take your "indexes love big blocks" paper. http://www.dba-oracle.com/oracle_tip...rge_blocks.htm No caveats, nothing (in an article titled "RULES for setting large blocksizes"). The evidence you point to? a count(*) from a FAST FULL SCAN and you say "that shows indexes like it, for RANGE SCANS", huh. that is trivial to prove "wrong", "not accurate", "not true". (you can try it yourself Mike, in sqlplus, you can prove to yourself that for an index range scan, a block size of INFINITY won't reduce the number of table access by index rowid's, and when range scanning, what contributes the preponderance of the LIO's??)

    In a singler user environment.

    Conclusively.

    Is that a performance proof? Nope, that is just showing how this thing called Oracle actually works

    That article boils down to

    o indexes love them
    o temp digs it
    o tpc-c does it, so it must be good

    (in fact, that is all that article says). That is the kind of 1/2 truth, misinformation that I'll aggresively respond to with "careful there, be very very careful. sounds all good, but careful with that axe eugene"

    ...

    sign me,

    sincerely
    a. gadfly
    this space intentionally left blank

  2. #2
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    My original response to reading the article.

    Originally posted by gandolf989
    Mike, it is true that I don't hang around CEO's and CIO's, but I was confused on one issue concerning your TPC Benchmark Example Look at page 379 for reference.

    I found this link from the article where you talk about using large block sizes, yet in one of your benchmarking examples almost all of the block sizes along with the default block size are 2k and in the other the default block size is 4k. I thought 2k block sizes went out with 7.1. 4k isn't very large either.

    It seems that from a management perspective it would be easier to use 8k for OLTP systems and 16k or 32k for datawarehouse systems. I realize that this approach is somewhat simplistic and certainly not all inclusive. But I'm not sure how using large block sizes in OLTP would help since most transactions would probably be small, most of the current data would be cached anyway, and if it weren't the OS is likely to grab multiple blocks on each read potentially causing Oracle to read more than it needs. It seems to me that the basic theory of your article is flawed, and would be seen as such to most DBA's.

    Can you explain why an article talking about using large block sizes is referencing a benchmark test where they are using small block sizes???
    Last edited by gandolf989; 04-14-2005 at 03:05 PM.
    this space intentionally left blank

  3. #3
    Join Date
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    Originally posted by gandolf989
    My oroginal response to reading the article.

    WOW!!

    A spelling error from the english major!!??
    This is exciting.
    I remember when this place was cool.

  4. #4
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    This is an anti-climax.
    I was hoping this would be a discussion on muscle cars.
    I remember when this place was cool.

  5. #5
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    Originally posted by Mr.Hanky
    WOW!!

    A spelling error from the english major!!??
    This is exciting.
    EET ME!!!
    this space intentionally left blank

  6. #6
    Join Date
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    over the hill and through the woods
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    *tear rolls down cheek*

    you two are killing me here.
    Oracle it's not just a database it's a lifestyle!
    --------------
    BTW....You need to get a girlfriend who's last name isn't .jpg

  7. #7
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    Originally posted by OracleDoc
    *tear rolls down cheek*

    you two are killing me here.
    Glad to be of service!!!

    But I really hoped that someone would offer me a well reasoned argument for or against this article. Honest!
    this space intentionally left blank

  8. #8
    Join Date
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    Location
    Netherlands
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    The best is when the three(gand,david and MH) get into a biaoutch_dead_lock. I guess we just need so real wicked news that'll kee them perplexed for the next couple of days.

    I was hoping the Ault/El burlo introduction to the forum would divert their attention, Maybe I'll ask Burlisun to join the obfuscation as well.
    Tarry Singh
    I'm a JOLE(JavaOracleLinuxEnthusiast)
    TarryBlogging
    --- Everything was meant to be---

  9. #9
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    Jan 2001
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    Bring it on beotches!!
    I remember when this place was cool.

  10. #10
    Join Date
    Aug 2003
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    Virginia
    Posts
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    You people keep the peanut gallery in stitches.....thanks a million!
    Bring Mike and Tom back. Please!

    I was hoping this would be a discussion on muscle cars.

    So.....anyone got a '71 Chevelle? I doubt OracleDoc, Terry and DaPi do, but I'll bite on the muscle car chat..........um.....anyone?

    OracleDoc, your sensitivity is causing me to weep uncontrolably
    Rick

    Sigh.....those were the days my friend, I thought they'd never end.
    I too remember when this place was coo.


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