1. What is use of LOG (Ver 7) option in EXP command?

The name of the file which log of the export will be written.

2. What is the use of FILE option in IMP command?

The name of the file from which import should be performed.

3. What is the use of SHOW option in IMP command?

A flag to indicate whether file content should be displayed or not.

4. What is the use of GRANT option in IMP command?

A flag to indicate whether grants on database objects will be imported.

5. What is the use of INDEXES option in IMP command?

A flag to indicate whether import should import index on tables or not.

6. What is the use of ROWS option in IMP command?

A flag to indicate whether rows should be imported. If this is set to 'N' then only DDL for database objects will be executed.

7. What is the use of RECORD option in EXP command?

For Incremental exports, the flag indirects whether a record will be stores data dictionary tables recording the export.

8. What is the use of INCTYPE option in EXP command?

Type export should be performed COMPLETE,CUMULATIVE,INCREMENTAL

11. What is the use of OWNER option in EXP command?

List of table accounts should be exported.

12. What is the use of FULL option in EXP command?

A flag to indicate whether full databse export should be performed.

13. What is the use of ANALYSE ( Ver 7) option in EXP command?

A flag to indicate whether statistical information about the exported objects should be written to export dump file.

14. What is the use of PARFILE option in EXP command?

Name of the parameter file to be passed for export.

15. What is the use of ROWS option in EXP command?

Flag to indicate whether table rows should be exported. If 'N' only DDL statements for the database objects will be created.

16. What is the use of INDEXES option in EXP command?

A flag to indicate whether indexes on tables will be exported.

17. What is the use of GRANT option in EXP command?

A flag to indicate whether grants on databse objects will be exported or not. Value is 'Y' or 'N'.

19. What is hot backup and how it can be taken?

Taking backup of archive log files when database is open. For this the ARCHIVELOG mode should be enabled. The following files need to be backed up. All data files. All Archive log, redo log files. All control files.

20. What is a logical backup?

Logical backup involves reading a set of database records and writing them into a file. Export utility is used for taking backup and Import utility is used to recover from backup.

21. What is cold backup? What are the elements of it?

Cold backup is taking backup of all physical files after normal shutdown of database. We need to take.
- All Data files.
- All Control files.
- All on-line redo log files.
- The init.ora file (Optional)

22. What are the different kind of export backups?

Full back - Complete database
Incremental - Only affected tables from last incremental date/full backup date.
Cumulative backup - Only affected table from the last cumulative date/full backup date.

23. List the factors that can affect the accuracy of the estimations?

The space used transaction entries and a deleted record does not become free immediately after completion due to delayed cleanout.
Trailing nulls and length bytes are not stored. Inserts of, updates to and deletes of rows as well as columns larger than a single datablock, can cause fragmentation and chained row pieces.

24. What is mean by Program Global Area (PGA)?

It is area in memory that is used by a Single Oracle User Process.

25. What is a Shared SQL pool?

The data dictionary cache is stored in an area in SGA called the Shared SQL Pool. This will allow sharing of parsed SQL statements among concurrent users.

26. What is SGA? How it is different from Ver 6.0 and Ver 7.0?

The System Global Area in a Oracle database is the area in memory to facilitates the transfer of information between users. It holds the most recently requested structural information between users. It holds the most recently requested structural information about the database. The structure is Database buffers, Dictionary cache, Redo Log Buffer and Shared SQL pool (ver 7.0 only) area.

27. How to implement the multiple control files for an existing database?

1. Edit init.ora file set control_files parameter with multiple location
2. shutdown immediate
3. copy control file to multiple locations & confirm from init.ora contol_files parameter
4. start the database.
5. run this query for changes confirmation - select name from v$controlfile;

28. What is redo log file mirroring?

Multiplexing Redo log file called Mirroing. ( Keeping multiple copies in different disks)

29. How redo logs can be achieved?

LGWR process wirtes all change vectors from theredo log buffer to online redo log file sequentially.

30. What is advantage of having disk shadowing / mirroring?

Shadow set of disks save as a backup in the event of disk failure. In most Operating System if any disk failure occurs it automatically switchover to place of failed disk.

Improved performance because most OS support volume shadowing can direct file I/O request to use the shadow set of files instead of the main set of files. This reduces I/O load on the main set of disks.

31. What is use of rollback segments in Oracle database?

When a user updated a particular table (for example 100 rows) the old value will be retained in the roll back segments(Oracle 8) and now it is Undo segment (oracle 9i). If the user issue a rollback command the old value will be taken from the rollback segment(that too if undo_retention parameter set properly in the parameter file).

32. What are disadvantages of having raw devices?

We should depend on export/import utility for backup/recovery (fully reliable) The tar command cannot be used for physical file backup, instead we can use dd command which is less flexible and has limited recoveries.

33. What is hit ratio?

Hit Ratio is the ratio of shared SQL and PL/SQL items found in the Library Cache versus physical storage.It can also be defined in a mathematical expression as 1 - ((physical reads) / (db block gets + consistent reads)).

34. What is a rollback segment entry?

When ever changes happend to the database previous change will be there in the rollback segment.

35. How will you create multiple rollback segments in a database?

create rollback segment roll1tablespace roll1.