Re: OBJECT DESING

Interesting, I hadn't previously heard that.

Makes sense though, indexes work that way by default. And you can't change that behavior.

Using a combination of PCTFREE and PCTUSED that adds up to 100 can lead to a lot of update activity on the free list.

Or at least I seem to recall that, I haven't actually experienced it. At least I dont' remember experiencing it. Everyone was a newbie at some point. :)

Jared

On Saturday 20 April 2002 09:33, Don Granaman wrote:
> For the radical approach - as espoused by Dave Ensor - PCTUSED=0 !!! (If
> this doesn't generate some serious discussion, I'll be amazed!)
>
> This works quite well for tables where records are purged some set length
> of time after insert. The net result is that blocks are filled, then left
> alone until purged when they (the vast majority at least) are completely
> emptied and put back on the free list. Blocks tend to be fully populated
> and freelist activity is minimized. Be aware that in some older versions
> of Oracle, there is a bug that requires PCTUSED = 1 (blocks only move back
> to the free list if used space < PCTUSED instead of <= PCTUSED). I do not
> know offhand what version fixed this.
>
> Dave Ensor's suggestion was to use this (almost) everywhere, but I'm not
> really comfortable with it as a blanket policy. It seems that tables with
> deletes that are "chronologically random" would end up with a LOT of very
> sparsely populated blocks.
>
> The approach recommended below is to set it rather high to accomplish the
> block density goal, but at the potential expense of high freelist activity.
> Which approach is more appropriate depends on the nature of one's
> insert/delete criteria.
>
> Also, PCTFREE can be set extremely low (1,5,?) for some kinds of objects -
> static tables, indexes with strictly inorder data (CREATE_DATE, SEQUENCE#,
> etc.).
>
> I agree with always setting PCTINCREASE =0
>
> Don Granaman
> [OraSaurus - Honk if you remember UFI !]
>
> ----- Original Message -----
> To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com>
> Sent: Thursday, April 18, 2002 8:08 AM
>
> > Seema,
> >
> > PCTINCREASE - always 0.
> >
> > PCTFREE - for lookup (code) tables = 10 for others, I use 20. My theory
>
> is
>
> > that lookup tables have little or no updates, so this value should be
>
> small.
>
> > If you have a high-update tables (columns that are updated a 8lot* after
>
> the
>
> > record was created, you may want a higher value here.
> >
> > PCTUSED - for lookup (code) tables = 90, for others, I use 80. Again,
> > for lookup tables with little or no updates, I fill the data blocks as
> > high as possible. For other tables, I currently use 80 as a starting
> > point.
> >
> > You will get many opinions here - read the docs to determine what you
>
> think
>
> > is best for you.
> >
> > Hope this helps.
> >
> > Tom Mercadante
> > Oracle Certified Professional

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