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This article mainly introduces "how to ensure that the submitted data will not be lost by Oracle". In daily operation, I believe many people have doubts about how to ensure that the submitted data will not be lost in Oracle. The editor has consulted all kinds of materials and sorted out simple and easy-to-use methods of operation. I hope it will be helpful to answer the doubt that "how can Oracle ensure that the submitted data will not be lost?" Next, please follow the editor to study!

1. The operation of Oracle when adding, deleting and modifying SQL

(1) when the user executes a DML statement without submission, the foreground process will write the modified data to the database buffer (step ①). At the same time, the modified data is written into the log buffer through the foreground process (step ②). At this point, the information between the database buffer and the data file is inconsistent.

(2) when the user executes the commit statement, Oracle only does one thing, that is, to trigger the LGWR (log writing process), and the log information will be written from the log buffer to the redo log file (step ④).

(3) when Oracle executes commit, it does not write the data from the database buffer to the data file (step ③), but writes the log to the log file. Oracle's log records all changes in Oracle data to ensure that the data is not lost. Therefore, the problem of data consistency can be understood as: data file + log file = database buffer.

(4) when the instance crashes, the data in the database buffer naturally does not exist. However, you can reconstruct the log of the database buffer through the data file + log file data to ensure that the data is not lost.

At this point, the study on "how to ensure that the data submitted by Oracle will not be lost" 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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