| SCN-Checkpoint-Log Switch [message #157366] |
Wed, 01 February 2006 23:58  |
gajini
Messages: 262
Registered: January 2006
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Senior Member |
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I studied that Log Switch causes Checkpoint to occur.It contradicts with some other concepts that i studied about checkpoint and SCN,can anyone clear my doubts,
1) Checkpoint causes DBWR to write dirty blocks to Datafile & redo log buffer contents to Redo Log file,when Log switch occurs,it causes checkpoint occurrence,my doubt is "In this case without any commit given,whether dirty blocks are written to Datafile or not.
2) The checkpoint occrrence during Log switch,updates an SCN value in Datafile header,Control file & Redo log files.Will this SCN value considered for restoring the db or SCN value which is assigned previously for a commit transaction is used?
Thanks in advance,
Malru
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| Re: SCN-Checkpoint-Log Switch [message #157626 is a reply to message #157366] |
Fri, 03 February 2006 10:23  |
aciolac
Messages: 242
Registered: February 2006
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Senior Member |
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1)Yes of course. I there are some opened transactions during checkpoint, this seem that all necessary information about this transactions contains in rollback segments - they also can be "dirty". So there have no one inconvience with documentation.
2)For recovering Oracle uses commit SCN . You can restore any transaction, beceause every transaction have their SCN.
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