RE: BCHR Tuning

GASP... you mean I'm not the ONLY one who does that from time to time. I feel so much better! :-)

>> WHEN does increasing the pctused to pctfree gap help ? And
>> should this be done by increasing the PCTFREE or decreasing
>> the PCTUSED -

>> ** It's a mistake I make quite often because of the image of
>> two lines across a data block representing the pctused and
>> pctfree levels. To push the pctfree line UP, you have to DECREASE
>> the pctfree value - and the entire paragraph was written from
>> the perspective of moving the lines, not changing the numbers.

-----Original Message-----
Lewis
Sent: Saturday, January 18, 2003 3:34 PM To: Multiple recipients of list ORACLE-L

Jared,

Thanks for the note - I loved the closing lines especially.

I have to say that I've already spotted two error in my note, one of them a silly slip, but the other is likely to cause confusion.

Silly slip - in the bit about decreasing block sizes -

    Good point - especially in Oracle 9; and especially if the     waits are for UNDO blocks, although that might (depending on     the nature of the activity) increase the waits on segment header     blocks

• That should have been "on the UNDO segment header blocks" in the last phrase - referring to the fact that a large transaction has to update its undo segment header block every time it fills an undo block and crosses into a new undo block.

Confusing comment - in the bit about the 'gap'

    WHEN does increasing the pctused to pctfree gap help ? And     should this be done by increasing the PCTFREE or decreasing     the PCTUSED -

• It's a mistake I make quite often because of the image of two lines across a data block representing the pctused and pctfree levels. To push the pctfree line UP, you have to DECREASE the pctfree value - and the entire paragraph was written from the perspective of moving the lines, not changing the numbers.

Regards

Jonathan Lewis
http://www.jlcomp.demon.co.uk

Coming soon a new one-day tutorial:
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-----Original Message-----
>
>Thanks Jonathan, for a breakdown on the cause and cure
>of buffer busy waits.
>

 . . .

>
>The abstract for one of Niemic's presentation at IOUG states
>that folks trying to encourage others to use some intelligence in
>maintaining their systems must have some vested interest.
>
>This works both ways I guess. :)
>

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