Sunday, May 15, 2011

What is LogMiner?

What is LogMiner ?

logMiner is a recovery utility. you can use it to recover the data from oracle redo log and archive log file. The Oracle LogMiner utility enables you to query redo logs through a SQLinterface.Redo logs contain information about the history of activity on a database.

see here, what logMiner can do and whats needs for logMiner?

- LogMiner is a utility which help us to extract the data from the redo logs (Online/Offline)
- When you run LogMiner, you need to specify the names of redo logs that you want to analyze
- LogMiner retrieves information from those redo logs and returns it through the V$LOGMNR_CONTENTS
- LogMiner only runs in Oracle version 8.1 or higher but you can use it to analyzes redo logs from release 8.0 or later database.
- The block size (DB_BLOCK_SIZE) of the analyzing instance must be identical to the block size of the log producing instance.
- If this is not the case, you will receive an error indicating the archive log is corrupted (when it is probably not).
- By default LogMiner returns all the rows in SCN order unless you have used the option COMMITTED_DATA_ONLY.
- The option COMMITTED_DATA_ONLY to specify that only committed transactions should be retrieved.
- SCN order is the order normally applied in media recovery

see Related posts:- how to use logMiner

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