In a datawarehouse, unless your ETL processes are very
slow and your loading window is quite small, you
should always favor the reading performance over the
loading performance.
I want to have the maximum rows per block so my
pctfree is always near 0 and pctused high.
You do not delete often in a DW but you truncate
tables and partition.
- "Koivu, Lisa" <lisa.koivu_at_efairfield.com> a
écrit : > Hi Vikas,
>
> The docs should have discussed the reason why. High
> pctused can lead to a
> block going on and off the freelist frequently as
> deletes/inserts are
> processed, and also can leave the amount of free
> space inadequate for a new
> insert (your avg_rowlen comes into play here). So
> what you'd end up with is
> several blocks on the freelist that don't have
> enough free space for an
> insert, and every time an insert is processed it
> goes thorugh the freelist
> and checks for space in the block. The performance
> hit comes when too many
> blocks have to be checked for adequate space. Does
> that make sense?
>
> Now some people on this list have debated that
> PCTFREE/PCTUSED is so low
> level and that performance really is not affected
> that much. Of course Ross
> was one of those people ("amen, my brother")
>
> HTH
> Lisa Koivu
> Data Bored Administrator
> Ft. Lauderdale, FL, USA
>
>
> > -----Original Message-----
> > From: Vikas Kawatra [SMTP:VKawatra_at_innoventry.com]
> > Sent: Friday, June 29, 2001 11:42 AM
> > To: Multiple recipients of list ORACLE-L
> > Subject: Setting PCTFREE & PCTUSED in a
> Datawarehouse
> >
> > I read in the Oracle docs that setting a high
> PCTUSED ( such as 60/70)
> > would
> > increase the cost of INSERTS to the table. Can
> someone explain this ,
> > pleas
> > e!
> >
> > thanks
> >
> > vikas
> > --
> > Please see the official ORACLE-L FAQ:
> http://www.orafaq.com
> > --
> > Author: Vikas Kawatra
> > INET: VKawatra_at_innoventry.com
> >
> > Fat City Network Services -- (858) 538-5051
> FAX: (858) 538-5051
> > San Diego, California -- Public Internet
> access / Mailing Lists
> >
>
> > To REMOVE yourself from this mailing list, send an
> E-Mail message
> > to: ListGuru_at_fatcity.com (note EXACT spelling of
> 'ListGuru') and in
> > the message BODY, include a line containing: UNSUB
> ORACLE-L
> > (or the name of mailing list you want to be
> removed from). You may
> > also send the HELP command for other information
> (like subscribing).
>
Stéphane Paquette
DBA Oracle, consultant entrepôt de données
Oracle DBA, datawarehouse consultant
stephane_paquette_at_yahoo.com
Do You Yahoo!? -- Pour faire vos courses sur le Net,
Yahoo! Shopping :
http://fr.shopping.yahoo.com
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: =?iso-8859-1?q?paquette=20stephane?=
INET: stephane_paquette_at_yahoo.com
Fat City Network Services -- (858) 538-5051 FAX: (858) 538-5051
San Diego, California -- Public Internet access / Mailing Lists
--------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in
the message BODY, include a line containing: UNSUB ORACLE-L
(or the name of mailing list you want to be removed from). You may
also send the HELP command for other information (like subscribing).
Received on Mon Jul 02 2001 - 02:31:57 CDT
