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Re: LMT with autoallocate

From: Connor McDonald <connor_mcdonald_at_yahoo.com>
Date: Wed, 23 May 2001 22:36:14 +0800
Message-ID: <3B0BCADE.7C28@yahoo.com>

Thomas Kyte wrote:
>
> A copy of this was sent to onlyforposting_at_yahoo.com (Vikas Agnihotri)
> (if that email address didn't require changing)
> On 22 May 2001 10:27:01 -0700, you wrote:
>
> >Since HJR doesnt have first-hand experience with autoallocate LMTs, I
> >wanted to check if these beasts are used in real-world production
> >databases at all.
> >
> >Could someone who has used LMT (locally managed tablespaces) with
> >either autoallocate or uniform extents comment on their alleged
> >performance benefits, administrative issues, etc?
> >
> >Would you recommend LMT over dictionary managed? If so, would you
> >recommend uniform or autoallocate?
> >
> >Thanks...
>
> locally managed tablespaces are (with the glaring exception of system) the ONLY
> type of tablespace I use. I only use UNIFORM, never autoallocate.
>
> I would definitely recommend them over dictionary managed. space management is
> a breeze with them (good bye recursive sql). free space fragmentation is a
> thing of the past -- I always hated pctincrease and with lmt's -- you don't have
> it at all. SMON doesn't spend half of its life looking for extents that might
> need coalescing. You never end up with tiny bits of free space that no object
> will be able to use (they are ALL the same size).
>
> You'll find that you group objects by size and growth into tablespace of various
> sizes. Do not be afraid (repeat do not be afraid) of objects with dozens or
> hundreds of extents -- it is really ok.
>
> I have found nothing wrong with lmt's to date.
> --
> Thomas Kyte (tkyte_at_us.oracle.com) Oracle Service Industries
> Howtos and such: http://asktom.oracle.com/
> Oracle Magazine: http://www.oracle.com/oramag
> Opinions are mine and do not necessarily reflect those of Oracle Corp

Besides a little bug that can munch 'exp full=y' when you have a lot of them, if memory serves one of the export views opens a cursor for every (tablespace/file/can't remember) and blew my open_cursors limit...

But I concur - they are Oracle's best invention for a long long time...

Cheers
Connor

-- 
===========================================
Connor McDonald
http://www.oracledba.co.uk (mirrored at
http://www.oradba.freeserve.co.uk)

"Some days you're the pigeon, some days you're the statue"
Received on Wed May 23 2001 - 09:36:14 CDT

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