Difference between the Checkpoint and SCN

Checkpoint
———-
Checkpoint in database is used to reduce the amount of the time for recovery. It is a background process in oracle(CKPT), which cause DBWR to write all the data blocks that have been modified since the last checkpoint to the datafile.
Checkpoint is responsible for
->Signaling DBWn
->Updating datafile headers with checkpoint info. (i.e. SCN)
->Updating Control file with checkpoint info. (i.e. scn)

SCN
—–
SCN is the ever increasing number to determine the age of database.
it’s System Change Number / System Commit Number…
It’s used to determine the consistency of database..
It’s stored at various places like control file, data files, redo log files.
If it doesn’t match, that means inconsistency..

So in short,
Checkpoint is the concept/background process while SCN is like serial number in our table..

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One Response

  1. I want to know more about the role of SCN in recovery on oracle DATABASE.

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