RE: locally managed with autoallocation

From: Adams, Matthew (GE Consumer & Industrial) <MATT.ADAMS_at_APPL.GE.COM>
Date: Fri, 27 Feb 2004 12:01:53 -0500
Message-ID: <F2AE82A3FD89334EA21F6C761C541A70678FAA@ap3expr06applge.appl.ge.com>

>, autoallocation helps me because when you set allocation type to uniform, the first extent is used for the bitmap.

> So, for example I create a tablespace and set allocation type
uniform=200mb.

> The tablespace will immediately display with 200MB already used.

Are you sure of this? This is not what I'm seeing in my testing. As long as I add

64K to a multiple of the extent size to hold the bitmap, it's fine.

using a size of 200m + 64K

create tablespace rma datafile '/db1_tst3/oracle/ts/data/rma.dbf' size 209780736
extent management local uniform size 50M;

Tablespace created

SQL> select bytes from sys.dba_free_space where tablespace_name = 'RMA';

BYTES

209715200

200 Meg available for use

Matt Adams - GE Appliances - matt.adams_at_appl.ge.com When I'm around hard-core computer geeks, I want to say, 'Come outside -- the graphics are great!'

Matt Weinhold

-----Original Message-----
From: Koivu, Lisa [mailto:Lisa.Koivu_at_Cendant-TRG.com] Sent: Friday, February 27, 2004 11:50 AM To: oracle-l_at_freelists.org
Subject: RE: locally managed with autoallocation

Hi Matt,

Well, for someone like me who doesn't have disk space to spare, autoallocation helps me because when you set allocation type to uniform, the first extent is used for the bitmap. So, for example I create a tablespace and set allocation type uniform=200mb. The tablespace will immediately display with 200MB already used.

Besides, the autoallocate extent sizes are all multiples of each other. I use autoallocate and I am very happy with it. Wasted space is kept to a minimum and the old rule of small/med/large objects in separate tablespaces is out the window, really. Having small and large objects in the same tablespace ensures that the small extents will indeed be used.

If you have the time to do the proper analysis to determine the correct extent size and categorize all your objects... well, more power to you. It just seems to me doing this is extra effort for very little benefit.

Just my two cents... fwiw...

Lisa Koivu

Monkey Mama

Orlando, FL, USA

-----Original Message-----
From: Adams, Matthew (GE Consumer & Industrial) [mailto:MATT.ADAMS_at_APPL.GE.COM]
Sent: Friday, February 27, 2004 11:37 AM To: 'oracle-l_at_freelists.org'
Subject: locally managed with autoallocation

I know we are WAY behind the times here, still using dictionary managed tablespaces for everything. I'm starting to evaluate methods for setting up tablespaces and have to ask this:

Why would anyone use autoallocation with locally managed tablespaces when it appears to be open to the same kind of honeycombing fragmentation problems that exist with dictionary tablespaces that don't use uniform extent sizes?

Natt

Matt Adams - GE Appliances - matt.adams_at_appl.ge.com When I'm around hard-core computer geeks, I want to say, 'Come outside -- the graphics are great!'

Matt Weinhold

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Received on Fri Feb 27 2004 - 10:59:20 CST