RE: locally managed tbs in 9i and extent sizes

From: Ehresmann, David <David.Ehresmann_at_ps.net>
Date: Wed, 16 Apr 2003 13:39:19 -0800
Message-ID: <F001.0058366E.20030416133919@fatcity.com>

List, I left everything the same except extent size. I thought I needed larger extents, wrong. The larger the faster it failed on import. I then went down in extent size. The statement:

create tablespace diamond datafile '/.../diamond_01.dbf' size 500m extent management local uniform size 40k;

works great with lots of space left over. The question is now: How small can I make the extent size 32k, 16k, or 8k? How do I determine the smallest extent size on the create tablespace statement I can use?
thanks,
David Ehresmann.

-----Original Message-----
Sent: Wednesday, April 16, 2003 11:34 AM To: Multiple recipients of list ORACLE-L

Richard,

But Oracle would coalesce on the fly, as necessary.

I forget the order of the first two (it's been awhile!) but as I recall, Oracle would look for:

1. an extent of exactly the same size as required
2. an extent larger than that required
3. "contiguous" extents that had not yet been coalesced which made up the correct size (or larger)

yeah, the good old days, when DBAs carved databases out of stone, and buffer cache hit ratios meant something and .... oh wait, what am I thinking!

Rachel
--- Richard Foote <richard.foote_at_bigpond.com> wrote:
> Hi Rachel,
>
> But until the "contiguous" extents get coalesced, they would be not
> be
> treated as contiguous by Oracle.
>
> They indeed were the days... ;)
>
> Cheers
>
> Richard
>
>
> > > more than the size of required extent. To know the largest
> available
> > > contiguous chunk of space, use
> > > ( select max(bytes) from dba_free_space where
> > > tablespace_name='<tablespace name>'; )
> >
> >
> > Actually that's not quite true, because it's possible for
> contiguous
> > extents to be listed in dba_free_space as two separate entries,
> > depending on when they were freed up and if they had been allocated
> at
> > different times.
> >
> > you'd need to see if there is an entry where block_id = prior
> > block_id+blocks
> >
> > back in the days before I used uniform extents, I had a script that
> > generated a report of contiguous space by tablespce. I don't need
> it
> > anymore, LMTs and uniform sizing has allowed me to stop worrying
> about
> > having contiguous space available.
> >
>
>
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author: Richard Foote
> INET: richard.foote_at_bigpond.com
>
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Author: Rachel Carmichael
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-- 
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-- 
Author: Ehresmann, David
  INET: David.Ehresmann_at_ps.net

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Received on Wed Apr 16 2003 - 16:39:19 CDT