Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Mailing Lists -> Oracle-L -> Re: Re: oracle docs do say # of extents effect performance

Re: Re: oracle docs do say # of extents effect performance

From: <rgaffuri_at_cox.net>
Date: Fri, 20 Jun 2003 11:37:34 -0700
Message-ID: <F001.005B6924.20030620112122@fatcity.com>


ok, so should the number of extents in a table be considered in table design? there are alot of .pdfs and people on this listserv that say it is irrelevant?
>
> From: Rachel Carmichael <[EMAIL PROTECTED]>
> Date: 2003/06/20 Fri PM 02:44:52 EDT
> To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]>
> Subject: Re: oracle docs do say # of extents effect performance
>
> or reasonable to WANT? if I'm running a data warehouse, maybe. If an
> OLTP system, orders and customers etc then I'm not likely to WANT the
> next block of data on disk for my transaction
>
>
> --- Darrell Landrum <[EMAIL PROTECTED]> wrote:
> > My favorite part is
> > "and all of the table's data will be stored in a relatively
> > contiguous
> > section of disk space".
> >
> > Is this even reasonable to believe, especially with any kind of
> > striping implemented?
> >
> > >>> [EMAIL PROTECTED] 06/20/03 12:00PM >>>
> > Two reasons:
> >
> > a) if you go into extent map blocks then you will
> > suffer an overhead of at least 1 billionth of a
> > percent :-)
> >
> > b) more seriously, its generally easier to pick up a
> > "rogue" table if its run into thousands of extents and
> > you had not intended it to. Its not a performance
> > problem per se, but its indicative that its a segment
> > thats doing something that was unforseen in the design
> > phase..
> >
> > hth
> > connor
> >
> > --- [EMAIL PROTECTED] wrote: > I just read a .pdf by a
> > couple of people at oracle
> > > called Stop Fragmenting and start living where it
> > > says not worry about the number of extents in a
> > > tablespace. However in the administrators doc it
> > > says the following:
> > >
> > > Estimate Table Size and Set Storage Parameters
> > > Estimating the sizes of tables before creating them
> > > is useful for the following reasons:
> > >
> > > You can use the combined estimated size of tables,
> > > along with estimates for indexes, rollback segments,
> > > and redo log files, to determine the amount of disk
> > > space that is required to hold an intended database.
> > > From these estimates, you can make correct hardware
> > > purchases and other decisions.
> > >
> > > You can use the estimated size of an individual
> > > table to better manage the disk space that the table
> > > will use. When a table is created, you can set
> > > appropriate storage parameters and improve I/O
> > > performance of applications that use the table. For
> > > example, assume that you estimate the maximum size
> > > of a table before creating it. If you then set the
> > > storage parameters when you create the table, fewer
> > > extents will be allocated for the table's data
> > > segment, and all of the table's data will be stored
> > > in a relatively contiguous section of disk space.
> > > This decreases the time necessary for disk I/O
> > > operations involving this table.
> > >
> > > this is at the following link:
> > >
> > >
> >
> http://download-west.oracle.com/docs/cd/A87860_01/doc/server.817/a76956/tables.htm#208
> >
> > >
> > > am I reading this wrong or is Oracle stating that
> > > you should have less extents in a table? I know
> > > several people on here have posted that the number
> > > of extents used by an object is almost irrelevant.
> > >
> > > --
> > > Please see the official ORACLE-L FAQ:
> > > http://www.orafaq.net
> > > --
> > > Author: <[EMAIL PROTECTED]
> > > INET: [EMAIL PROTECTED]
> > >
> > > Fat City Network Services -- 858-538-5051
> > > http://www.fatcity.com
> > > San Diego, California -- Mailing list and web
> > > hosting services
> > >
> > ---------------------------------------------------------------------
> > > To REMOVE yourself from this mailing list, send an
> > > E-Mail message
> > > to: [EMAIL PROTECTED] (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).
> >
> > =====
> > Connor McDonald
> > web: http://www.oracledba.co.uk
> > web: http://www.oaktable.net
> > email: [EMAIL PROTECTED]
> >
> > "GIVE a man a fish and he will eat for a day. But TEACH him how to
> > fish, and...he will sit in a boat and drink beer all day"
> >
> >
> ________________________________________________________________________
> > Want to chat instantly with your online friends? Get the FREE Yahoo!
> > Messenger http://uk.messenger.yahoo.com/
> > --
> > Please see the official ORACLE-L FAQ: http://www.orafaq.net
> > --
> > Author: =?iso-8859-1?q?Connor=20McDonald?=
> > INET: [EMAIL PROTECTED]
> >
> > Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> > San Diego, California -- Mailing list and web hosting services
> > ---------------------------------------------------------------------
> > To REMOVE yourself from this mailing list, send an E-Mail message
> > to: [EMAIL PROTECTED] (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.net
> > --
> > Author: Darrell Landrum
> > INET: [EMAIL PROTECTED]
> >
> > Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> > San Diego, California -- Mailing list and web hosting services
> > ---------------------------------------------------------------------
> > To REMOVE yourself from this mailing list, send an E-Mail message
> > to: [EMAIL PROTECTED] (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).
>
>
> __________________________________
> Do you Yahoo!?
> SBC Yahoo! DSL - Now only $29.95 per month!
> http://sbc.yahoo.com
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author: Rachel Carmichael
> INET: [EMAIL PROTECTED]
>
> Fat City Network Services -- 858-538-5051 http://www.fatcity.com
> San Diego, California -- Mailing list and web hosting services
> ---------------------------------------------------------------------
> To REMOVE yourself from this mailing list, send an E-Mail message
> to: [EMAIL PROTECTED] (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.net
-- 
Author: <[EMAIL PROTECTED]
  INET: [EMAIL PROTECTED]

Fat City Network Services    -- 858-538-5051 http://www.fatcity.com
San Diego, California        -- Mailing list and web hosting services
---------------------------------------------------------------------
To REMOVE yourself from this mailing list, send an E-Mail message
to: [EMAIL PROTECTED] (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 Fri Jun 20 2003 - 13:37:34 CDT

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US