What is stored in the redo log?

What is stored in the redo log?

My question is regarding the contents of the redo log. When I perform any DML operation, does my DML (insert/update/delete) statement get stored directly into the redo log? My undersatnding of things is that any of the DML statments get stored in the redo log as such (say Insert into emp values(10) ), likewise in sql_redo of redo log and inverse statement to this in sql_undo. In the undo segment, only values get stored. If I am not correct, please explain in full detail or give me the exact link where I can get the answer satifactorily.

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What is stored in the redo log? You get both the redo (the statement that was executed) and undo (a reversing statement). LogMiner provides a great way to look at the contents of the redo logs (see v$logmnr_contents for a list of all the values LogMiner "mines" from the redo logs).

If you want to get more info on what the redo logs store, see the Oracle Concepts Guide and also most documentation/papers on LogMiner gives a good overview of redo. You can get the Oracle docs at http://technet.oracle.com and a google.com search will provide you with numerous links for info on LogMiner.

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This was first published in January 2003

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