Re: I am confused re PCTFREE and PCTUSED...

Nasir,

Here is my 2 cents :

With PCTFREE=20 and PCTUSED=40 (defaults)

• On original load of a table (let's say with an import), blocks will be filled up to 80% (leaving 20% free).
• Once the block is filled to 80%, it is no longuer available for new rows.
• Deletion of rows might free this block down from the 80% to 70, 60 and then 50% but it won't be available for new rows until the highwater mark goes down below 40%...
• Throwing in UPDATEs in the equation does not change this behavior much but might create "chained rows".....

Regards,

Marc Mazerolle
InforMaze Technologies

NNOOR wrote:

> Hi,
>
> Following is straight from Oracle documentation
> re: PCTFREE and PCTUSED: "After the free space in a data
> block reaches PCTFREE, no new rows are inserted in that
> block until the percentage of space used falls below PCTUSED."
>
> I am a little confused. Say that PCTFREE is 20 (default) and
> PCUSED is 40 (default). Does that mean, that any given time
> (assuming updates do not occur at a very high rate, and if
> they do, they do not change the data size significantly), the
> maximum space used in a block is only 40%?---20% is left free
> for updates, and data base will stop inserting rows into the
> block when it reaches 40% used. Am I drawing correct conclusions
> from the statement quoted above?
>
> Thanks and Regards,
> Nasir Noor (nnoor_at_cris.com)
Received on Wed May 26 1999 - 10:10:13 CDT