Hot backups

Oracle introduced hot backups back in version 6, allowing us take hot backups of our database tablespaces without the need to shut down the database like in earlier versions. Moreover in version 10g, Oracle gave us the ability to take hot backups of the entire database, making our life a little more easy. When executing a user-managed backup online, Oracle stops recording checkpoints to all the associated datafiles.

Let's take a deeper look at what's happening internally in the database when we use the BEGIN BACKUP option:

  • A hot backup flag in the datafiles header is set
  • A checkpoint occurs, flashing all dirty blocks from memory to disk, synchronizing all the datafile headers to the same SCN, and freezing the headers for consistency, ...

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