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Extents and blocks [message #326587] Thu, 12 June 2008 01:24 Go to next message
aslamkhalife
Messages: 42
Registered: July 2007
Location: India
Member
Hi

I have few queries regarding EXTENTS

1. Why large object should have uniform extent size?
2. Why small object should be place in auto allocate?
3. Exactly what will be the large and small object size in Oracle?
4. How can one decide the size of uniform extent clause?
5. How does the block and extent work in Oracle?

Please guide....

Aslam
Re: Extents and blocks [message #326608 is a reply to message #326587] Thu, 12 June 2008 02:04 Go to previous messageGo to next message
Michel Cadot
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Registered: March 2007
Location: Nanterre, France, http://...
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1. No reason, "should" is wrong.
2. No reason, "should" is wrong. It is just easier to manage
3. What you want, it is not an Oracle notion
4. As you want, the best is to not use it, use autoallocate
5. See Database Concepts

Regards
Michel
Re: Extents and blocks [message #326624 is a reply to message #326608] Thu, 12 June 2008 02:19 Go to previous messageGo to next message
aslamkhalife
Messages: 42
Registered: July 2007
Location: India
Member
Hi,

Presently one our DEV db has the autoallocate = system
It means the initial extent size is by default 64kb and the PCTINCREASE is by default 50, which result in next extent to be much more larger to initial one and also further the extent size goes on increasing........
because of this space is been wasted......

Now how can I stop this wastage.......

Thanks
Aslam.






Re: Extents and blocks [message #326696 is a reply to message #326624] Thu, 12 June 2008 05:25 Go to previous messageGo to next message
Michel Cadot
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Quote:
It means the initial extent size is by default 64kb and the PCTINCREASE is by default 50

This is wrong.
system/autoallocate means Oracle chooses the size.

Regards
Michel
Re: Extents and blocks [message #327532 is a reply to message #326587] Mon, 16 June 2008 15:41 Go to previous messageGo to next message
JackyShu
Messages: 25
Registered: May 2008
Junior Member
uniform extent size to avoid fragments, but of course, if you set huge extent size for a small table, space might be wasted. Laughing
Re: Extents and blocks [message #327569 is a reply to message #327532] Mon, 16 June 2008 23:24 Go to previous messageGo to next message
Michel Cadot
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Quote:
uniform extent size to avoid fragments,

Autoallocate too.

Regards
Michel
Re: Extents and blocks [message #327575 is a reply to message #326587] Mon, 16 June 2008 23:51 Go to previous messageGo to next message
aslamkhalife
Messages: 42
Registered: July 2007
Location: India
Member
Hi Michel,

I dint understand you last reply....

"Quote:
uniform extent size to avoid fragments,
Autoallocate too."


Regards
Aslam
Re: Extents and blocks [message #327601 is a reply to message #327575] Tue, 17 June 2008 00:41 Go to previous messageGo to next message
Michel Cadot
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Autoallocate/system allocation also prevent from fragmenting as well as uniform.
Assuming "fragmenting" means leaving never used free holes.

Regards
Michel

[Updated on: Tue, 17 June 2008 00:42]

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Re: Extents and blocks [message #327607 is a reply to message #326587] Tue, 17 June 2008 00:57 Go to previous messageGo to next message
aslamkhalife
Messages: 42
Registered: July 2007
Location: India
Member
Hi

How can one decide bout

AUTOALLOCATE or UNIFORM clause.

What things should be kept in mind while creating tablespace

Thanks
Aslam
Re: Extents and blocks [message #327613 is a reply to message #327607] Tue, 17 June 2008 01:05 Go to previous messageGo to next message
Michel Cadot
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Location: Nanterre, France, http://...
Senior Member
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Quote:
4. As you want, the best is to not use it, use autoallocate


Regards
Michel
Re: Extents and blocks [message #327615 is a reply to message #326587] Tue, 17 June 2008 01:08 Go to previous message
aslamkhalife
Messages: 42
Registered: July 2007
Location: India
Member
Thanks Michel,

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