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Re: INITIAL and NEXT extent sizing question

From: Eric Lansu <eric.lansu_at_quicknet.nl>
Date: Wed, 27 Sep 2000 16:43:46 +0200
Message-Id: <10632.117995@fatcity.com>


In Oracle 8i there's no real limit to the number of extents. I use a max of 4096, and a working max of 1024 extents. I have 2 xtent sizes 160K and 5M

5M * 1024 = 5Gb, a rather big table without partitioning etc....

Logical next steps could be 160Mb and 5Gb

You can force this uniform sizing from 8.1 on :-)

Eric Lansu

> The theory behind uniform init and entents is the reduction of
fragmentation and wasted space. If you use 1 large extent and then truncate the table a lot of small extents can reuse the space freed up but is the extent sizes are a mixed bag then the space usage can and will leave a lot of holes that are not big enough for an extent. Thus fragmentation.
> ROR
>
> >>> Deepender_Gupta_at_escorts.co.in 09/27/00 08:55AM >>>
>
> But Oracle says that we try to have our table in not more than 5 extents.
> What is the advantage of having more extents of smaller size as opposed
to
> having 1 big
> extent.
>
> Kindly elaborate.
> Deepender
>
>
>
>
>
> To: Multiple recipients of list ORACLE-L
<ORACLE-L_at_fatcity.com>@SMTP_at_AMG1
> cc:
>
> Hi
>
> It would all depend on the table. If the table is not going to grow
> then the NEXT should be set low (Hence the table would not extend).
> If the table would be continually growing then the NEXT should be
> sized accordingly to allow for inserts.
> Try not to make the NEXT too big (>1GB)
> eg. You rather have 4 * 500M extents as opposed to having 1 * 4GB
> extent.
>
> HTH
> Suhen
>
> >>> Venkat_Kalepalli_at_satyam.com 09/26/00 02:51PM >>>
> I think U can set NEXT also same as INITIAL.
>
>
> Venkat
> Ph:7846101- Extn: 5648
>
> > ----------
> > From: Fred Smith[SMTP:fred_fred_1_at_hotmail.com]
> > Reply To: ORACLE-L_at_fatcity.com
> > Sent: Monday, September 25, 2000 10:05 PM
> > To: Multiple recipients of list ORACLE-L
> > Subject: INITIAL and NEXT extent sizing question
> >
> > I have a table with rows currently populating. I wish to resize the
> table
> >
> > for better performance. What is the best way I should figure out how
> to
> > size my INITIAL and NEXT extent sizes for this table. Is it just:
> > 1) Analyze the table
> > 2) SELECT BLOCKS * (block_size) from dba_tables for the table in
> question
> > =
> > what the initial size should be set to.
> > 3) What determines what I should set the NEXT extent size to then?
Received on Wed Sep 27 2000 - 09:43:46 CDT

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