| What is the System Change Number? [message #241567] |
Wed, 30 May 2007 01:10  |
trantuananh24hg
Messages: 744
Registered: January 2007
Location: Ha Noi, Viet Nam
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Senior Member |
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Dear all and especially Michel!
I am wondering about the SCN - System Change Number. I know it is a sequence number whenever Database is being opened reset log. But I don't know where is the view V$ to see it, and when does SCN occur?
Would you like to guide me, and send me a document (or link) to learn about it carefully?
Thank you very much!
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| Re: What is the System Change Number? [message #241580 is a reply to message #241567] |
Wed, 30 May 2007 01:40  |
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Michel Cadot
Messages: 68651
Registered: March 2007
Location: Nanterre, France, http://...
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Senior Member
Account Moderator |
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SQL> select current_scn from v$database;
CURRENT_SCN
--------------------
4339477155665
1 row selected.
SQL> select dbms_flashback.get_system_change_number from dual;
GET_SYSTEM_CHANGE_NUMBER
------------------------
4339477155666
1 row selected.
Many things can change SCN mostly user and internal commits.
As you can see in my example, I was alone on my db but the time I typed the 2 statements SCN increased of 1.
SCN is just a tick (like clock tick) to measure db internal time (like clock measures "real" time).
Regards
Michel
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