| Kaiz |
Posted: Mar 15, 2008 09:50:22 AM |
Total Post: 104
Joined: Sep, 2007
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Dear Friends....
One point I doubt that I am not clear... which I want to share with u all...
When we do DML operation on a table i.e. I have updated one value... the old data will be store in undoblock in buffer_cache along with the new data in datablock... first and than it is transfer into redolog buffer and than bring down in the redolog file before DBWm writes in the datafile... i.e. undo block in undo segment and datablock in the respected file in a tablespace.... Is this correct what I am understanding or my concepts are wrong....
Thanks & Regards.... |
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 Gitesh |
| Posted: Mar 16, 2008 11:24:56 PM |  |
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Total Post: 322
Joined: May, 2005
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When DML operation performs that time Oracle change block image in buffer cache. Undo tablespace contains old entry. Oracle also write DML operation entry with SCN number with block version number in the redo log buffer.
When user issue commit that time Oracle store commit entry in the redolog buffer and end the transaction in to Undo. Same time redolog buffer flush in redolog file.Same time physical datafile never update or contains newer /modified entry. When checkpoint occurs that time datafile will contain new/modified data.This time buffers will be flush from the buffer cache and writes in datafile.
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| Kaiz |
| Posted: Mar 17, 2008 01:17:38 AM | |
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Total Post: 104
Joined: Sep, 2007
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Thanks Gitesh Brother.....
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| Time Zone: EDT |
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