No, because if Oracle wasn't choosing an index, it
would be a db file scattered read. In other words, a
full scan. I meant an index, f.e, with bad cardinality
or the values you need have a bad distribution.
Regards.
--- Anjo Kolk <anjo_at_oraperf.com> wrote:
> That is the 1st problem that I mentioned (too many
> I/Os because Oracle
> doesn't use an index for example).
>
> Anjo.
>
> Christian Trassens wrote:
>
> > Or Oracle is choosing an awful index. Check the
> > execution plan.
> >
> > Regards.
> > --- Robertson Lee - lerobe <lerobe_at_acxiom.co.uk>
> > wrote:
> > > Not my solution, just something I was meaning to
> > > try.
> > >
> > > -----Original Message-----
> > > Sent: 25 February 2002 11:18
> > > To: Multiple recipients of list ORACLE-L
> > >
> > >
> > >
> > > Performance problems with db file sequential
> read
> > > can happen for two
> > > reasons:
> > > 1) you are doing too many I/O
> > > 2) each I/O is too slow (now there can many
> reaons
> > > why I/O is slow).
> > >
> > > So your solution of going with the INDEX_FFS
> hint is
> > > too reduce the number
> > > of
> > > I/O. Well what if the problem is that the I/O is
> too
> > > slow ?
> > >
> > > Anjo Kolk
> > >
> > > http://www.oraperf.com
> > >
> > >
> > > Robertson Lee - lerobe wrote:
> > >
> > > > All,
> > > >
> > > > Oracle 8.0.5.0.0 Tru64 4.0f
> > > >
> > > > We are having a performance issue with one of
> our
> > > applications and it
> > > looks
> > > > like it is pointing to the db file sequential
> > > reads event. I have been
> > > doing
> > > > some digging around and a recommendation in a
> book
> > > I have has suggested a
> > > > possible way to alleviate this is to use the
> > > INDEX_FFS hint in the query.
> > > > Anyone used this before ??. or indeed any
> other
> > > recommendations where I
> > > > should be looking.
> > > >
> > > > Regards
> > > >
> > > > Lee
> > > >
> > > > The information contained in this
> communication is
> > > > confidential, is intended only for the use of
> the
> > > recipient
> > > > named above, and may be legally privileged. If
> the
> > > reader
> > > > of this message is not the intended recipient,
> you
> > > are
> > > > hereby notified that any dissemination,
> > > distribution or
> > > > copying of this communication is strictly
> > > prohibited.
> > > > If you have received this communication in
> error,
> > > please
> > > > re-send this communication to the sender and
> > > delete the
> > > > original message or any copy of it from your
> > > computer
> > > > system.
> > > > --
> > > > Please see the official ORACLE-L FAQ:
> > > http://www.orafaq.com
> > > > --
> > > > Author: Robertson Lee - lerobe
> > > > INET: lerobe_at_acxiom.co.uk
> > > >
> > > > 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).
> > >
> > >
> > > --
> > > Please see the official ORACLE-L FAQ:
> > > http://www.orafaq.com
> > > --
> > > Author: Anjo Kolk
> > > INET: anjo_at_oraperf.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).
> > > --
> > > Please see the official ORACLE-L FAQ:
> > > http://www.orafaq.com
> > > --
> > > Author: Robertson Lee - lerobe
> > > INET: lerobe_at_acxiom.co.uk
> > >
> > > 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).
> >
> > =====
> > Ing. Christian Trassens
> > Senior DBA & Unix Administrator
> > Phone: 0034-699240979
> > 0034-649824704
> >
> > __________________________________________________
> > Do You Yahoo!?
> > Yahoo! Sports - Coverage of the 2002 Olympic Games
> > http://sports.yahoo.com
> > --
> > Please see the official ORACLE-L FAQ:
> http://www.orafaq.com
> > --
> > Author: Christian Trassens
> > INET: ctrassens_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).
>
>
> --
> Please see the official ORACLE-L FAQ:
> http://www.orafaq.com
> --
> Author: Anjo Kolk
> INET: anjo_at_oraperf.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).
Ing. Christian Trassens
Senior DBA & Unix Administrator
Phone: 0034-699240979
0034-649824704
Do You Yahoo!?
Yahoo! Sports - Coverage of the 2002 Olympic Games
http://sports.yahoo.com
--
Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Christian Trassens
INET: ctrassens_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 Feb 25 2002 - 09:48:39 CST
