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There are 3 essential elements of any database system
- Datafiles – storage
- Memory – in oracle its the SGA
- Processes – To operate on the data files and memory
Storage
- Datafiles
- Contains data
- Tables
- Indexes
- Undo segments (used to be rollback segments)
- Temporary files
- Oracle is easy as DIRT – Data, Index, Rolback, Temp
- In Oracle you can now have around 65000 datafiles
Important views for the DBA
- dba_data_files
- v$dbfile
- v$datafile
Control files.
Should have 3 identical control files on different disks and controllers
They contain information about the database
- db name
- created date
- path to data files
- check point info
Important Views
- v$controlfile