Your example block can be 60% full and not be on the free list.
Once your block reaches 90% full, it is removed from the free list.
It will not be put on the free list again until used space in the block
falls below PCTUSED, which is 40% in your example.
So, a block fills up, it is removed from the free list, then a couple of
rows are deleted and used space falls to 60%. The block is still
not on the free list, as the space used has remained above 40%.
Guess what can happen when PCTFREE + PCTUSED = 100?
Not sure what you're reading, but you should be reading the concepts
manual, as it explains this all rather well.
HTH
Jared
| Maryann Atkinson <[EMAIL PROTECTED]>
Sent by: [EMAIL PROTECTED] 11/04/2003 03:09 PM
|
To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]> cc: Subject: PCTFREE and PCTUSED |
Suppose I have the following settings which happen to be
the defaults as well:
PCTFREE 10
PCTUSED 40
I am trying to figure out what PCTUSED is really used for.
My book is telling me that is used so that Oracle knows
whether to keep a block in the "free-list".
My point is this: If PCTFREE is 10%, that means the block can be
up to 90% full, right?
Well, if the block happens to be 60% full at the moment, then Oracle
knows that this block is not full enough because 60 is less than 90,
so it can keep it in the free list. I dont see what PCTUSED is needed,
it kind of seems I can accomplish the same with just one parm,
that being PCTFREE.
But Oracle wouldnt have just put a parm there without any usage,
so I guess there's something I dont see...
Any ideas/examples? Any good reasoning anywhere?
Thanks,
maa
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Author: Maryann Atkinson
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