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Rollback Segments are used :
To generate read-consistent database information during database
recovery to rollback uncommitted transactions for users.
43. What is a Temporary Segment ?
Temporary segments are created by ORACLE when a SQL statement
needs a temporary work area to complete execution. When the
statement finishes execution, the temporary segment extents are
released to the system for future use.
44. What is a Data File ?
Every ORACLE database has one or more physical data files. A
database's data files contain all the database data. The data of
logical database structures such as tables and indexes is
physically stored in the data files allocated for a database.
45. What are the Characteristics of Data Files ?
A data file can be associated with only one database.Once created a
data file can't change size.
One or more data files form a logical unit of database storage
called a tablespace.
46. What is a Redo Log ?
The set of Redo Log files for a database is collectively known as
the database's redo log.
47. What is the function of Redo Log ?
The Primary function of the redo log is to record all changes made to
data.
48. What is the use of Redo Log Information ?
The Information in a redo log file is used only to recover the database
from a system or media failure prevents database data from being
written to a database's data files.
49. What does a Control file Contain ?
A Control file records the physical structure of the database. It
contains the following information.
Database Name
Names and locations of a database's files and redolog files.
Time stamp of database creation.
50. What is the use of Control File ?
When an instance of an ORACLE database is started, its control file is
used to identify the database and redo log files that must be
opened for database operation to proceed. It is also used in database
recovery.
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