Oracle-L: RE: Coalescing tablespace

From: Mercadante, Thomas F <NDATFM_at_labor.state.ny.us>
Date: Mon, 27 Oct 2003 07:44:25 -0800
Message-ID: <F001.005D4B04.20031027074425@fatcity.com>

Dick,

You said:

"I think the Server Technologies folks need to spend a little more time with SMON. It certainly does not appear to pull it's due."

I think they avoided the issue with Locally Managed Tablespaces. All of these problems go away with standardized extent sizes.

Tom Mercadante
Oracle Certified Professional

-----Original Message-----
Sent: Monday, October 27, 2003 10:19 AM
To: Multiple recipients of list ORACLE-L

Cary,

Hang on a second. Oracle will not always coalesce on create to the extent needed. It will go out either 10 or 20 extents (rusty memory here) and then give up. In this case it will either create an extent of the size requested above all of the other objects in the tablespace or return an error. I've found the coalesce command extremely useful since you really don't want pctincrease > 0 due to it's obscene behavior. It is the only way you can build a decent sized table in a tablespace that's broken up into tiny adjacent chunks.

Case in point, we were trying to clean up a PeopleSoft mess where PSINDEX was busted up into millions of 16K extents. Part of the exercise was to relocate several indexes into their own tablespaces & then try to reclaim some unused space. Well, no problem, Oracle coalesces tablespaces on create, right. NAW, every index create statement failed just like the tablespace was full when we knew it was totally empty. Coalesced the tablespace & they all succeeded.

PS: I think the Server Technologies folks need to spend a little more time with SMON. It certainly does not appear to pull it's due.

Dick Goulet
Senior Oracle DBA
Oracle Certified 8i DBA

-----Original Message-----
Sent: Monday, October 27, 2003 1:34 AM
To: Multiple recipients of list ORACLE-L

You mean "make your PCTINCREASE 0 so that SMON will *not* coalesce them." Right? Some comments:

You don't want SMON coalescing your tablespaces. It is a complete waste of time. Oracle coalesces on demand during a CREATE statement.
The SMON coalesce feature was added under protest by the smart people in Server Technologies development, in response to pressure from Marketing and Support so that the Oracle RDBMS would look better in brochures.
Thank goodness the developers made SMON smart enough to *not* coalesce freespace in any tablespace with PCTINCREASE set to 0 (which is what it *should* be set to almost everywhere).
You can turn off SMON's ridiculous CPU-consuming, lock-holding behavior by setting event 10269.

Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com

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-----Original Message-----
Mladen Gogala
Sent: Sunday, October 26, 2003 8:09 PM
To: Multiple recipients of list ORACLE-L

Well, having in mind that you're working on version 7 (chuckle) , you should
make your tablespaces have PCTINCREASE 0 (alter tablespace default storage...)
so SMON will coalesce them. You may also try (I'm not sure whether this has
existed before 7.3) with alter tablespace coalesce, which should mark the
tablespace to be coalesced by SMON at he first opportunity. I'm afraid that
PCTINCREASE 0 is your best option.

On 2003.10.26 20:04, Ross Collado wrote:
> Hi,
> For those like me still working on an Oracle 716 (hold the laughs),
how do
> we coalesce a tablespace?
> Rgds,
> Ross
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author: Ross Collado
> INET: Ross.Collado_at_techpac.com
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-- 
Mladen Gogala
Oracle DBA
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Please see the official ORACLE-L FAQ: http://www.orafaq.net
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Author: Mladen Gogala
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Author: Mercadante, Thomas F
  INET: NDATFM_at_labor.state.ny.us

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Received on Mon Oct 27 2003 - 09:44:25 CST