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Deffered Segment Management + RMAN Backup [message #517803] Thu, 28 July 2011 06:09 Go to next message
dkdms2124
Messages: 369
Registered: April 2010
Location: INDIA
Senior Member

Hi All,

We all know about the new feature introduced in Oracle 11g ie. "Deffered Segment Space management" in which there in no segment allocated to table which is empty, which means that only the data is going to be inserted in the table the first segment is going to be allocated.

I created a user assinged a default tablespace to it, created 3 tables, two of them having data and 1 empty table.

When I did export using the export utility, I found that the empty table was not included however the same situation contradicted when I did the export using "EXPDP".

I want to know is the samething of tables missing in export happen in RMAN backup of the tablespace which I have assigned to that user.

Thanks
Deepak
Re: Deffered Segment Management + RMAN Backup [message #517805 is a reply to message #517803] Thu, 28 July 2011 06:22 Go to previous messageGo to next message
Michel Cadot
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1/ It is the expected behaviours (for both exp and expdp)
2/ Yes, the table does NOT exist in the tablespace, just in Oracle dictionary (just like a view)

Regards
Michel

[Updated on: Thu, 28 July 2011 06:22]

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Re: Deffered Segment Management + RMAN Backup [message #517806 is a reply to message #517805] Thu, 28 July 2011 06:27 Go to previous messageGo to next message
dkdms2124
Messages: 369
Registered: April 2010
Location: INDIA
Senior Member

So If I take RMAN backup of tablespace and restore it, the tables will not exist- RIGHT !

Regards
Deepak
Re: Deffered Segment Management + RMAN Backup [message #517808 is a reply to message #517806] Thu, 28 July 2011 06:54 Go to previous messageGo to next message
Michel Cadot
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Right.
If you need this ask Oracle to create the segment when you create the table:
CREATE TABLE ... SEGMENT CREATION IMMEDIATE ...
or set it at instance/session level:
ALTER SYSTEM/SESSION SET DEFERRED_SEGMENT_CREATION=false;

Regards
Michel
Re: Deffered Segment Management + RMAN Backup [message #517813 is a reply to message #517808] Thu, 28 July 2011 07:12 Go to previous messageGo to next message
dkdms2124
Messages: 369
Registered: April 2010
Location: INDIA
Senior Member

I took the RMAN backup of the tablespace assingned as default to the user.

Take the tablespace offline, deleted the datafile and then restore the tablespace from the RMAN backup but the empty table was still there. WHY?

Thanks
Deepak
Re: Deffered Segment Management + RMAN Backup [message #517814 is a reply to message #517813] Thu, 28 July 2011 07:26 Go to previous messageGo to next message
Michel Cadot
Messages: 68043
Registered: March 2007
Location: Nanterre, France, http://...
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Because it is ONLY in the dictionary and NOT in the tablespace.
Think it as a view and you will understand.

Regards
Michel

[Updated on: Thu, 28 July 2011 08:14]

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Re: Deffered Segment Management + RMAN Backup [message #517815 is a reply to message #517814] Thu, 28 July 2011 07:43 Go to previous message
dkdms2124
Messages: 369
Registered: April 2010
Location: INDIA
Senior Member

Thanks for your help Sir, got it.

Regards
Deepak
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