Please send your Questions & Answers or Feedback to "dvmadhavreddy@javabook.org"

Please send your Questions & Answers or Feedback to "mohan@javabook.org"

What is Oracle Database ?

Oracle Database is nothing but collection of important files(C R D files).
                1.Control files
                2.Redo Log files
                3.Data files
The minimum number of data files that are required to create a database are 2.
                                1.system.dbf
                                2.sysaux.dbf
In 10g version of oracle, oracle has introduced sysaux.dbf.

The minimum number of online Redo Log groups that are required to create a database are 2.
                e.g : redo1a.log, redo1b.log
the minimum number of control files that are required to create a database is 1.
                e.g : control01.ctl
All the 3 physical files of the database are binary in nature and not recommended to edit them either with vi editor or notepad.
In version 9i, the minimum size size of online redo log file is 64K where as from 10g it is 4MB.
Every data file will have its own header which contains information related to the data file
                SCN(System Sequence Number)
                Log Sequence Number
                CheckPoint Change Number
                Absolute File Number
                Relative File Number
Absolute File Number uniquely identifies the data file within the database.
Relative File Number uniquely identifies the data file within the TableSpace.

For every 3 seconds, oracle generates one number(SCN) and updates to the data file header as well as Control file.
Whenever we issue startup/shutdown oracle generates SCN and it will be updated to the data file header as well as Control file.

Related Posts Plugin for WordPress, Blogger...

Flag Counter