Re: PCTUSED & PCTFREE Q's

In article <46lenu$9il_at_bcarh8ab.bnr.ca>, jp_at_vivaldi.plaza.nt.com (JP Srinath) wrote:

> This might sound too simple question to answer But still need an explanation
>
> Assume the following
>
> PCTFREE 15 --> which means that ORACLE Datablock will be used to insert rows
> till atleast 15% of the space in the block is free - right ?
> And after that the remaining 15% is set aside for only updates.
>
> PCTUSED 40 --> Which I suppose means that once Datablock is 85% full ( because
> PCTFREE is 15 ) - NO MORE ROWS would be inserted into
 that block
> till used part of the block falls below 39% - right ?
>
> Does this mean that once Datablock is 85% full - we are actually
 setting aside
> 60% of space in the block ?? - By waiting for used part of the block to
 fall below 39% ??
>
> Now my question is - Doesn't it contradict PCTFREE 15 - i.e., only 15%
 is set aside and
> implies that it should be able to INSERT ROWS as long as used part of
 the block is
> less than 85 % as against 39 % ?
>
>
> Any insights appreciated
>

Reply:    

         The assumption being made is that PCFREE + PCTUSED =100. This is not so. The above sum is deliberately made less than 100 so that the datablock does not frequently come into and go out of the free list. Since the updation of the free list is an overhead.
>

 Venkat
> ~
Received on Wed Oct 25 1995 - 00:00:00 CET