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This article mainly introduces "what is the role of Oracle redo log files". In daily operation, I believe many people have doubts about the role of Oracle redo log files. The editor consulted all kinds of materials and sorted out simple and easy-to-use methods of operation. I hope it will be helpful for you to answer the doubts about "what is the use of Oracle redo log files?" Next, please follow the editor to study!

1. What is Redo log?

The Oracle redo log (redo log) is used to record operation entries for database data recovery. In order to improve efficiency, oracle usually recommends setting up three sets of redo log.

Oracle redo log groups usually have four states, namely unused,inactive,active,current.

Unused: usually refers to a log group that has never been used, that is, a newly added log group.

Current: the LGWR process is writing the log of redo log buffer to the log group.

Active: the state after the log switch has just been completed. At this time, the data changes caused by the transactions committed in the log group have not been fully written to the data file from DB buffer cache, so the log group cannot be overwritten and becomes inactive after it is fully written. If the database is in archive mode, the archive is completed in that state.

Inactive: the log of the status can be overwritten and can be written to the log. If you are in archiving mode, this stage proves that the archiving has been completed.

Performance comparison of 2.3group redo log 50m and five groups of redo log 500m

After using these two methods for a service pair that operates the database frequently, the awr report is exported for the corresponding time period.

Then compare the seven main directions as shown in the following figure, the awr on the left is 5-500 and the awr on the right is 3-50:

1. Comparison indicator 1

two。 Comparison indicator 2

3. Yes, indicator 3

4. Comparison indicator 4

5. Comparison indicator 5

6. Comparison index 6

7. Comparison indicator 7

At this point, the study on "what is the role of Oracle redo log files" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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