i understand, but alot of people have posted here that its ok to have smaller extents
anyway.
who is correct? or am i missing something?
>
> From: "Richard Ji" <[EMAIL PROTECTED]>
> Date: 2003/06/20 Fri PM 02:00:11 EDT
> To: Multiple recipients of list ORACLE-L <[EMAIL PROTECTED]>
> Subject: RE: oracle docs do say # of extents effect performance
>
> Even without stripping you can't gaurantee it will be a contiguous
> section of disk space. The file could be scattered across
> the file system.
>
> Richard Ji
>
> -----Original Message-----
> Sent: Friday, June 20, 2003 1:12 PM
> To: Multiple recipients of list ORACLE-L
>
>
> 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
> > --
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> > INET: [EMAIL PROTECTED]
> >
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> =====
> Connor McDonald
> web: http://www.oracledba.co.uk
> web: http://www.oaktable.net
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>
> "GIVE a man a fish and he will eat for a day. But TEACH him how to
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Received on Fri Jun 20 2003 - 13:18:50 CDT
