Re: PCTFREE and PCTUSED

Hi!

Note that a block can come off freelist also when it's usage is under PCTFREE but above PCTUSED *and* an insert is attempted, but rejected for this block because it would have filled the block above PCTFREE.

Tanel.

• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Wednesday, November 05, 2003 1:34 AM

> To use your numbers, the block can fill to 90% (100-PCTFREE) at which
> time it comes off the freelist.
>
> If you delete rows until the block falls below 40% used (PCTUSED), the
> block will go back on the freelist.
>
> -----Original Message-----
> Sent: Tuesday, November 04, 2003 3:09 PM
> To: Multiple recipients of list ORACLE-L
>
>
> 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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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Tanel Poder
  INET: tanel.poder.003_at_mail.ee

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