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DBA Interview Questions 3

What is Row Migration and Row Chaining?
There are two circumstances when this can occur, the data for a row in a table may be too large to fit into a single data block. This can be caused by either row chaining or row migration.
Chaining: Occurs when the row is too large to fit into one data block when it is first inserted. In this case, Oracle stores the data for the row in a chain of data blocks (one or more) reserved for that segment. Row chaining most often occurs with large rows, such as rows that contain a column of data type LONG, LONG RAW, LOB, etc. Row chaining in these cases is unavoidable.
Migration: Occurs when a row that originally fitted into one data block is updated so that the overall row length increases, and the block’s free space is already completely filled. In this case, Oracle migrates the data for the entire row to a new data block, assuming the entire row can fit in a new block. Oracle preserves the original row piece of a migrated row to point to the new block containing the migrated row: the rowid of a migrated row does not change. When a row is chained or migrated, performance associated with this row decreases because Oracle must scan more than one data block to retrieve the information for that row.
  1. INSERT and UPDATE statements that cause migration and chaining perform poorly, because they perform additional processing.
  2. SELECTs that use an index to select migrated or chained rows must perform additional I/Os.
Detection: Migrated and chained rows in a table or cluster can be identified by using the ANALYZE command with the LIST CHAINED ROWS option. This command collects information about each migrated or chained row and places this information into a specified output table. To create the table that holds the chained rows,
execute script UTLCHAIN.SQL.
SQL> ANALYZE TABLE scott.emp LIST CHAINED ROWS;
SQL> SELECT * FROM chained_rows;
You can also detect migrated and chained rows by checking the ‘table fetch continued row’ statistic in the v$sysstat view.
SQL> SELECT name, value FROM v$sysstat WHERE name = ‘table fetch continued row’;
Although migration and chaining are two different things, internally they are represented by Oracle as one. When detecting migration and chaining of rows you should analyze carefully what you are dealing with.
What is Ora-01555 - Snapshot Too Old error and how do you avoid it?
1. Increase the size of rollback segment. (Which you have already done)
2. Process a range of data rather than the whole table.
3. Add a big rollback segment and allot your transaction to this RBS.
4. There is also possibility of RBS getting shrunk during the life of the query by setting optimal.
5. Avoid frequent commits.
6. Google out for other causes.
What is a locally Managed Tablespace?
A Locally Managed Tablespace is a tablespace that manages its own extents maintaining a bitmap in each data file to keep track of the free or used status of blocks in that data file. Each bit in the bitmap corresponds to a block or a group of blocks. When the extents are allocated or freed for reuse, Oracle changes the bitmap values to show the new status of the blocks. These changes do not generate rollback information because they do not update tables in the data dictionary (except for tablespace quota information), unlike the default method of Dictionary - Managed Tablespaces.
Following are the major advantages of locally managed tablespaces –
• Reduced contention on data dictionary tables 
• No rollback generated 
• No coalescing required 
• Reduced recursive space management.
Can you audit SELECT statements?
      Yes, we can audit the select statements. Check out the below example:
SQL> show parameter audit
NAME TYPE VALUE
———————————— ———– ——————————
audit_file_dest string E:\ORACLE\PRODUCT\10.2.0\DB_2\
ADMIN\SRK\ADUMP
audit_sys_operations boolean FALSE
audit_trail string NONE
SQL>  begin
dbms_fga.add_policy ( object_schema => ‘SCOTT’,
object_name => ‘EMP2′,
policy_name => ‘EMP_AUDIT’,
statement_types => ‘SELECT’ );
end;
/
PL/SQL procedure successfully completed.
SQL>select * from dba_fga_audit_trail;
             no rows selected
In HR schema:
SQL> create table bankim(
name varchar2 (10),
roll number (20));
Table created.
SQL> insert into bankim values (‘bankim’, 10);
1 row created.
SQL> insert into bankim values (‘bankim2′, 20);
1 row created.
SQL> select * from bankim;
NAME ROLL
———- ———-
bankim 10
bankim2 20
SQL> select name from bankim;
NAME
———-
bankim
bankim2
In sys schema:
SQL>set head off
SQL> select sql_text from dba_fga_audit_trail;
select count(*) from emp2
select * from emp2
select * from emp3
select count(*) from bankim
select * from bankim
select name from bankim
What does DBMS_FGA package do?
The dbms_fga Package is the central mechanism for the FGA is implemented in the package dbms_fga, where all the APIs are defined. Typically, a user other than SYS is given the responsibility of maintaining these policies. With the convention followed earlier, we will go with the user SECUSER, who is entrusted with much of the security features. The following statement grants the user SECUSER enough authority to create and maintain the auditing facility.
Grant execute on dbms_fga to secuser;
The biggest problem with this package is that the polices are not like regular objects with owners. While a user with execute permission on this package can create policies, he or she can drop policies created by another user, too. This makes it extremely important to secure this package and limit the use to only a few users who are called to define the policies, such as SECUSER, a special user used in examples.
What is Cost Based Optimization?
The CBO is used to design an execution plan for SQL statement. The CBO takes an SQL statement and tries to weigh different ways (plan) to execute it. It assigns a cost to each plan and chooses the plan with smallest cost.
The cost for smallest is calculated: Physical IO + Logical IO / 1000 + net IO.
How often you should collect statistics for a table?
CBO needs some statistics in order to assess the cost of the different access plans. These statistics includes:
Size of tables, Size of indexes, number of rows in the tables, number of distinct keys in an index, number of levels in a B* index, average number of blocks for a value, average number of leaf blocks in an index
These statistics can be gathered with dbms_stats and the monitoring feature.
How do you collect statistics for a table, schema and Database?
Statistics are gathered using the DBMS_STATS package. The DBMS_STATS package can gather statistics on table and indexes, and well as individual columns and partitions of tables. When you generate statistics for a table, column, or index, if the data dictionary already contains statistics for the object, then Oracle updates the existing statistics. The older statistics are saved and can be restored later if necessary. When statistics are updated for a database object, Oracle invalidates any currently parsed SQL statements that access the object. The next time such a statement executes, the statement is re-parsed and the optimizer automatically chooses a new execution plan based on the new statistics.
Collect Statistics on Table Level
sqlplus scott/tiger
exec dbms_stats.gather_table_stats ( -
     ownname          => 'SCOTT', -
     tabname          => 'EMP', -
     estimate_percent => dbms_stats.auto_sample_size, -
     method_opt       => 'for all columns size auto', -
     cascade          => true, -
     degree           => 5 - )
/
Collect Statistics on Schema Level
sqlplus scott/tiger
exec dbms_stats.gather_schema_stats ( -
     ownname          => 'SCOTT', -
     options          => 'GATHER', -
     estimate_percent => dbms_stats.auto_sample_size, -
     method_opt       => 'for all columns size auto', -
     cascade          => true, -
     degree           => 5 - )

Collect Statistics on Other Levels
DBMS_STATS can collect optimizer statistics on the following levels, see Oracle Manual
GATHER_DATABASE_STATS
GATHER_DICTIONARY_STATS
GATHER_FIXED_OBJECTS_STATS
GATHER_INDEX_STATS
GATHER_SCHEMA_STATS
GATHER_SYSTEM_STATS
GATHER_TABLE_STATS
Can you make collection of Statistics for tables automatic?
Yes, you can schedule your statistics but in some situation automatic statistics gathering may not be adequate. It suitable for those databases whose object is modified frequently. Because the automatic statistics gathering runs during an overnight batch window, the statistics on tables which are significantly modified during the day may become stale.
There may be two scenarios in this case:                           
·         Volatile tables that are being deleted or truncated and rebuilt during the course of the day.
·         Objects which are the target of large bulk loads which add 10% or more to the object’s total size.
So you may wish to manually gather statistics of those objects in order to choose the optimizer the best execution plan. There are two ways to gather statistics.
  1. Using DBMS_STATS package.
  2. Using ANALYZE command
How can you use ANALYZE statement to collect statistics?
ANALYZE TABLE emp ESTIMATE STATISTICS FOR ALL COLUMNS;
ANALYZE INDEX inv_product_ix VALIDATE STRUCTURE;
ANALYZE TABLE customers VALIDATE REF UPDATE;
ANALYZE TABLE orders LIST CHAINED ROWS INTO chained_rows;
ANALYZE TABLE customers VALIDATE STRUCTURE ONLINE;
To delete statistics:
ANALYZE TABLE orders DELETE STATISTICS;
To get the analyze details:
SELECT owner_name, table_name, head_rowid, analyze_timestamp FROM chained_rows;
On which columns you should create Indexes?
The following list gives guidelines in choosing columns to index:
  • You should create indexes on columns that are used frequently in WHERE clauses.
  • You should create indexes on columns that are used frequently to join tables.
  • You should create indexes on columns that are used frequently in ORDER BY clauses.
  • You should create indexes on columns that have few of the same values or unique values in the table.
  • You should not create indexes on small tables (tables that use only a few blocks) because a full table scan may be faster than an indexed query.
  • If possible, choose a primary key that orders the rows in the most appropriate order.
  • If only one column of the concatenated index is used frequently in WHERE clauses, place that column first in the CREATE INDEX statement.
  • If more than one column in a concatenated index is used frequently in WHERE clauses, place the most selective column first in the CREATE INDEX statement.
What type of Indexes is available in Oracle?
  • B-tree indexes: the default and the most common.
  • B-tree cluster indexes: defined specifically for cluster.
  • Hash cluster indexes: defined specifically for a hash cluster.
  • Global and local indexes: relate to partitioned tables and indexes.
  • Reverse key indexes: most useful for Oracle Real Application Clusters.
  • Bitmap indexes: compact; work best for columns with a small set of values
  • Function-based indexes: contain the pre-computed value of a function/expression Domain indexes: specific to an application or cartridge.
What is B-Tree Index?
B-Tree is an indexing technique most commonly used in databases and file systems where pointers to data are placed in a balance tree structure so that all references to any data can be accessed in an equal time frame. It is also a tree data structure which keeps data sorted so that searching, inserting and deleting can be done in logarithmic amortized time.
A table is having few rows, should you create indexes on this table?
You should not create indexes on small tables (tables that use only a few blocks) because a full table scan may be faster than an indexed query.
A Column is having many repeated values which type of index you should create on this column
B-Tree index is suitable if the columns being indexed are high cardinality (number of repeated values). In fact for this situation a bitmap index is very useful but bitmap index are vary expensive.
When should you rebuild indexes?
There is no thumb rule “when you should rebuild the index”. According to expert it depends upon your database situation:
When the data in index is sparse (lots of holes in index, due to deletes or updates) and your query is usually range based or If Blevel >3 then takes index in rebuild consideration; desc DBA_Indexes;
Because when you rebuild indexes then database performance goes down.
In fact binary tree index can never be unbalanced. Binary tree performance is good for both small and large tables and does not degrade with the growth of table.
Can you build indexes online?
Yes, we can build index online. It allows performing DML operation on the base table during index creation. You can use the statements:
CREATE INDEX ONLINE and DROP INDEX ONLINE.
ALTER INDEX REBUILD ONLINE is used to rebuild the index online.
A Table Lock is required on the index base table at the start of the CREATE or REBUILD process to guarantee DDL information. A lock at the end of the process also required to merge change into the final index structure.
A table is created with the following setting
                storage (initial 200k
                   next 200k
                   minextents 2
                   maxextents 100
                   pctincrease 40)
What will be size of 4th extent?
Percent Increase allows the segment to grow at an increasing rate.
The first two extents will be of a size determined by the Initial and Next parameter (200k)
The third extent will be 1 + PCTINCREASE/100 times the second extent (1.4*200=280k).
AND the 4th extent will be 1 + PCTINCREASE/100 times the third extent (1.4*280=392k!!!) and so on...
Can you Redefine a table Online?
Yes. We can perform online table redefinition with the Enterprise Manager Reorganize Objects wizard or with the DBMS_REDEFINITION package.
It provides a mechanism to make table structure modification without significantly affecting the table availability of the table. When a table is redefining online it is accessible to both queries and DML during the redefinition process.
Purpose for Table Redefinition
·         Add, remove, or rename columns from a table
·         Converting a non-partitioned table to a partitioned table and vice versa
·         Switching a heap table to an index organized and vice versa
Modifying storage parameters
·         Adding or removing parallel support
·         Reorganize (defragmenting) a table
·         Transform data in a table
Restrictions for Table Redefinition:
·         One cannot redefine Materialized Views (MViews) and tables with MViews or MView Logs defined on them.
·         One cannot redefine Temporary and Clustered Tables
·         One cannot redefine tables with BFILE, LONG or LONG RAW columns
·         One cannot redefine tables belonging to SYS or SYSTEM
·         One cannot redefine Object tables
·         Table redefinition cannot be done in NOLOGGING mode (watch out for heavy archiving)
·         Cannot be used to add or remove rows from a table
Can you assign Priority to users?
Yes, we can do this through resource manager. The Database Resource Manager gives a database administrators more control over resource management decisions, so that resource allocation can be aligned with an enterprise's business objectives.
With Oracle database Resource Manager an administrator can:
  • Guarantee certain users a minimum amount of processing resources regardless of the load on the system and the number of users
  • Distribute available processing resources by allocating percentages of CPU time to different users and applications.
  • Limit the degree of parallelism of any operation performed by members of a group of users
  • Create an active session pool. This pool consists of a specified maximum number of user sessions allowed to be concurrently active within a group of users. Additional sessions beyond the maximum are queued for execution, but you can specify a timeout period, after which queued jobs terminate.
  • Allow automatic switching of users from one group to another group based on administrator-defined criteria. If a member of a particular group of users creates a session that runs for longer than a specified amount of time, that session can be automatically switched to another group of users with different resource requirements.
  • Prevent the execution of operations that are estimated to run for a longer time than a predefined limit
  • Create an undo pool. This pool consists of the amount of undo space that can be consumed in by a group of users.
  • Configure an instance to use a particular method of allocating resources. You can dynamically change the method, for example, from a daytime setup to a nighttime setup, without having to shut down and restart the instance.

Windows Administrator Interview Questions I


Question # 1
What is a desktop?
Answer:-
When you start your computer, the first thing you see is the desktop. The desktop is your work area.


Question # 2
Define Taskbar?
Answer:-
By default, the taskbar is located on the bottom edge of the desktop. You can click the taskbar and drag it to other locations. The Start button, active program buttons, icons for quick access to programs, and the current time are located on the taskbar.


Question # 3
Define My Computer?
Answer:-
The My Computer icon provides access to the resources on your computer. You can access your drives and other peripherals by clicking on the My Computer icon.


Question # 4
Define Recycle Bin?
Answer:-
When you delete an object, Windows XP sends it to the Recycle Bin. You can restore objects that are located in the Recycle Bin or you can permanently delete them.


Question # 5
Define Internet Explorer?
Answer:-
The Internet Explorer icon launches the Internet Explorer browser.


Question # 6
Define Shortcut Icon?
Answer:-
Icons with an arrow in the lower left corner are shortcut icons. Click the icon for quick access to the object they represent (program, document, printer, and so on).


Question # 7
Define Program, folder, and document icons?
Answer:-
Program, folder, and document icons do not have an arrow in the lower left corner. They represent the actual object and provide direct access to the object.


Question # 8


How to start a program?
Answer:-
To start a program:
1)    Click the Start button, located in the lower left corner of your screen.
2)    Highlight Programs. The Program menu will appear.
3)    Move to the Program menu and highlight the program you want to start. If you see a right pointer next to your selection, a sub-menu will appear. Refine your choice by highlighting the appropriate selection on the sub-menu. Continue until you get to the final sub-menu.
4)    Click the program name to start the program.


Question # 9
How to add an item located on my desktop to the Start or to a Program menu?
Answer:-
To add an item on the desktop to the Start or to a Program menu:
1)    Click and drag the item on top of the Start button.
2)    Release the mouse button when the Start menu appears.
3)    The item will appear on the Start menu.
4)    If you would prefer to have the item on a Program menu or sub-menu of the Start menu, drag the item from the Start menu to the Program menu or sub-menu.


Question # 10
What is Windows Explorer?
Answer:-
Windows Explorer is a place where you can view the drives on your computer and manipulate the folders and files. Using Windows Explorer, you can cut, copy, paste, rename, and delete folders and files.


Question # 11
How to open Windows Explorer?
Answer:-
To open Windows Explorer:
1)    Click the Start button, located in the lower left corner of your screen.
2)    Highlight programs.
3)    Highlight Accessories.
4)    Click Windows Explorer.


Question # 12
How to add an item located in Windows Explorer to the Start menu or to a Program menu?
Answer:-
To add an item located in Windows Explorer to the Start menu or to a  Program menu:
*    Click the Start button. The Start menu will appear.
*    Highlight Settings. A submenu will appear.
*    Click Taskbar and Start Menu. A dialog box will appear.
*    Click the Start Menu tab.
*    Click the Customize button.
*    Click Add.
*    Type the path to the item you want to add, or use Browse to navigate to the item.
*    Click Next.
*    Double-click an appropriate folder for the item.
*    Click Finish.
*    Click OK.
*    Click OK again. The item will appear on the menu.


Question # 13
How to remove an item from the Start menu or from a Program menu?
Answer:-
To remove an item from the Start menu or from a Program menu:
*    Click the Start button. The Start menu will appear.
*    Highlight Settings. A submenu will appear.
*    Click Taskbar and Start Menu. A dialog box will appear.
*    Click the Start Menu tab.
*    Click Customize.
*    Click the Remove button.
*    Find and click the item you want to remove.
*    Click the Remove button. You will be prompted.
*    Click Yes.
*    Click Close.
*    Click OK.


*    Click OK again.


Question # 14
How to copy an item that is located on the Start menu or on a Program menu?
Answer:-
To copy an item located on the Start menu or on a Program menu:
1)    Highlight the item.
2)    Right-click. A context menu will appear.
3)    Click Copy.


Question # 15
How to rename an item on the Start menu or on a Program menu?
Answer:-
To rename an item on the Start menu or on a Program menu:
1)    Highlight the item.
2)    Right-click the item.
3)    Click Rename. The Rename dialog box will appear.
4)    Type the new name in the New Name field.
5)    Click OK.


Question # 16
How to delete a file from the Start menu or from a Program menu?
Answer:-
To delete a file from the Start menu or from a Program menu:
1)    Highlight the item.
2)    Right-click.
3)    Click Delete. You will be prompted.
4)    Click Yes.


Question # 17
How to re-sort the Start or a Program menu?
Answer:-
To resort a menu:
1)    Go to the menu.
2)    Right-click.
3)    Click Sort By Name.


Question # 18
How to quickly find files and folders?
Answer:-
Windows XP enables you to quickly locate files and folders on your drives. The search option provides you with four search options: Pictures, music, or video; Documents; All files and folders; and Computers and people. To quickly find a file or folder:
*    Click the Start button. The Start menu will appear.
*    Highlight Search.
*    Click Files or Folders. The Search Results dialog box will open.
*    Choose an option.
*    Enter your search criteria. Use the table that follows to help you.
*    Click search. The results of your search will appear in the right pane.


Question # 19
How to shut down Computer?
Answer:-
To shut down computer:
1)    Click the Start button. The Start menu will appear.
2)    Click Turn Off Computer. The Turn Off Computer dialog box will appear.
3)    Click the Turn Off icon. Your computer will shut down.


Question # 20
How to restart Computer?
Answer:-


You may need to shut down and restart your computer after installing a new program or if your system becomes unstable. To shut down and immediately restart your computer:
1)    Click the Start button. The Start menu will appear.
2)    Click Turn Off Computer. The Turn Off Computer dialog box will appear.
3)    Click the Restart icon. Your computer will restart.


Question # 21
What is Standby mode?
Answer:-
When your computer is in the Standby mode, your computer consumes less electricity, but is ready for immediate use. However, if the computer loses electrical  power while in the standby mode, any information you have not saved will be lost.


Question # 22
How to put Computer in Standby mode?
Answer:-
To put your computer in Standby mode:
1)    Click the Start button. The Start menu will appear.
2)    Click Turn Off Computer. The Turn Off Computer dialog box will appear.
3)    Click the Stand By icon.


Question # 23
Define the field "Look In" in search result?
Answer:-
Select the drive or folder you want to search.


Question # 24
Define the field "A word or phrase in the file" in search result?
Answer:-
If you are looking for a file that has a specific word or phrase in the file, enter the word or phrase in this field.


Question # 25
Define the field "Specify Dates" in search result?
Answer:-
Select from Modified, Created, or Last Accessed. Select Modified to find all files modified since the date criteria you enter, select Created to find all files created since the date criteria you enter, or select Last Accessed to find all files accessed since the date criteria you enter.


Question # 26
Define the field "All or part of the file (document) name" in search result?
Answer:-
Enter the file-name, the first few letters of the file-name, or any letters found in the file-name. Use the * as a wild card. For example, to find all of the files that begin with r and end in the extension .doc, enter r*.doc. To find files that begin with resume and have any extension, enter resume.
If you are looking for a file that has a specific word or phrase in the file-name, enter the word or phrase in this field.


Question # 27
Define the field "Between/During the Previous" in search result?
Answer:-
Specify the date search criteria you want to use. Between allows you to search for files modified, created, or accessed between two dates. During allows you to search for files modified, created, or accessed during the previous number of days or months you specify.


Question # 28
Which is the most recently used document list?
Answer:-
As you work, Windows XP tracks the last 15 files you used. It lists these files on the Most Recently Used Document list. To view the Most Recently Used Document list:
*    Click the Start button.
*    Highlight Documents. The most recently used documents will display.


*    To open a file listed on the Most Recently Used Document list, click the file name.


Question # 29
How to clear my Most Recently Used Document list?
Answer:-
To clear the Most Recently Used Document list:
*    Click the Start button. The Start menu will appear.
*    Highlight Settings.
*    Click Taskbar and Start menu. A dialog box will appear.
*    Click the Start Menu tab.
*    Click Customize.
*    Click Clear.
*    Click OK.
*    Click OK again.


Question # 30
How to change the date and/or time?
Answer:-
To change the date and/or time:
*    Click the Start button, which is located in the lower left corner of the screen. The Start menu will appear.
*    Highlight Settings. A submenu will appear.
*    Click Control Panel. The Control Panel will open.
*    Click Date/Time. The Date/Time Properties dialog box will appear.


Question # 31
How to change the date and/or time in date frame?
Answer:-
*    In the Date frame, select the month and year.
*    In the Month field, click to open the drop-down menu and select the current month.
*    Type the year in the Year field or use the arrows next to the field to move forward or backward until you get to the current year.
*    The Time field is divided into four segments: hour, minutes, seconds, and AM and PM. To make an adjustment:
*    Click in the segment and either type in the correct information or use the arrow keys on the right side to select the correct hour, minute, second or AM or PM.


Question # 32
How to change the time zone?
Answer:-
*    Click the Time Zone tab.
*    Choose the correct time zone from the drop-down menu.
*    If you want the clock to automatically adjust to daylight saving time, check the box on the screen.
*    Click the Apply button.
*    Click OK.


Question # 33
How to install a new printer?
Answer:-
To install a new printer:
*    Make sure your printer is plugged in, connected to your computer, turned on, and has paper in it.
*    Click the Start button. The Start menu will appear.
*    Highlight Settings. A submenu will appear.
*    Click Printers and Faxes. The Printers and Faxes control panel will appear.
*    Double-click on Add Printer. The Add Printer Wizard will open.
*    Follow the onscreen instructions.


Question # 34
How to cancel every print job?
Answer:-
To cancel every print job:
*    Click the Start button. The Start menu will appear.
*    Highlight Settings. A submenu will appear.
*    Click Printers and Faxes. The Printers and Faxes control panel will appear.
*    Double-click the printer to which you sent the print jobs. The Printer window will open.
*    Click Printer, which is located on the menu bar.
*    Click Cancel All Documents.

Windows Administrator Interview Questions II




Question # 35
How to cancel a print job?
Answer:-
To cancel a print job:
*    Click the Start button. The Start menu will appear.
*    Highlight Settings. A submenu will appear.
*    Click Printers and Faxes. The Printers and Faxes control panel will appear.
*    Double-click the printer to which you sent the print jobs. The Printer window will open.
*    Click the job you want to stop. If you want to stop more than one job, hold down the Control key while you click the additional jobs.
*    Click Document, which is located on the menu bar.
*    Click Cancel.


Question # 36
How to restart print jobs which temporarily stopped?
Answer:-
To restart a print job you temporarily stopped:
*    Click the Start button. The Start menu will appear.
*    Highlight Settings. A sub-menu will appear.
*    Click Printers and Faxes. The Printers and Faxes control panel will appear.
*    Double-click the printer to which you sent the print job. The Printer window will open.
*    Click the documents you paused. If more than one document has been paused, hold down the Ctrl key as you click the additional documents.
*    Click Document, which is located on the menu bar.
*    Click Pause. The check-mark next to Pause should disappear.


Question # 37
How to temporarily stop selected jobs from printing?
Answer:-
To temporarily stop selected jobs from printing:
*    Click the Start button. The Start menu will appear.
*    Highlight Settings. A submenu will appear.
*    Click Printers and Faxes. The Printers and Faxes control panel will appear.
*    Double-click the printer to which you sent the print job. The Printer window will open.
*    Click the document you want to pause. If you want to pause more than one document, hold down the Control key as you select the additional documents.
*    Click Document, which is located on the menu bar.
*    Click Pause. A check-mark should appear next to Pause.


Question # 38
Suppose if temporarily stopped all of the print jobs and now I want to restart them. How do I do that?
Answer:-
To restart a print queue that has been stopped:
*    Click the Start button. The Start menu will appear.
*    Highlight Settings. A sub-menu will appear.
*    Click Printers and Faxes. The Printer control panel will appear.
*    Double-click the printer to which you sent the print job. The Printer window will open.
*    Click Printer, which is located on the menu bar. A drop-down menu will appear.
*    Click Pause Printing. The check-mark next to Pause Printing should disappear.


Question # 39
How to temporarily stop all jobs from printing?
Answer:-
To temporarily stop all jobs from printing:
*    Click the Start button. The Start menu will appear.
*    Highlight Settings. A sub-menu will appear.
*    Click Printers. The Printer control panel will appear.
*    Double-click the printer to which you sent the print jobs. The Printer window will open.
*    Click Printer, which is located on the menu bar. A drop-down menu will appear.
*    Click Pause Printing. A check-mark should appear next to Pause Printing.


Question # 40
How to create a desktop shortcut?
Answer:-
To create a shortcut to an item located on the Start menu:


*    Click Start. The Start menu will appear.
*    Locate the item to which you want to create a shortcut. If the item is located on a sub-menu, go to the sub-menu.
*    Click and drag the item to your desktop.


Question # 41
What is desktop shortcut?
Answer:-
A desktop shortcut, usually represented by an icon, is a small file that points to a program, folder, document, or Internet location. Clicking on a shortcut icon takes  you directly to the object to which the shortcut points. Shortcut icons contain a small arrow in their lower left corner. Shortcuts are merely pointers deleting a shortcut will not delete the item to which the shortcut points.


Question # 42
How to create a shortcut to items visible in Windows Explorer?
Answer:-
*    Open Windows Explorer.
*    Minimize the Windows Explorer window.
*    Locate in Windows Explorer the item to which you want to create a shortcut.
*    Hold down the right mouse button and drag the item onto the desktop.
*    Release the right mouse button. A context menu will appear.
*    Click Create Shortcuts Here.


Question # 43
How to turn a Web link into a desktop shortcut?
Answer:-
To turn a Web link into a desktop shortcut, click the link in your browser window (usually underlined text) and drag it to the desktop. An icon will appear on your desktop. When you click the icon, your browser will open and you will go directly to the Web page.


Question # 44
How to delete a desktop shortcut?
Answer:-
To delete a shortcut:
*    Click the shortcut.
*    Press the Delete key.
*    Click Yes.


Question # 45
How to rename a desktop shortcut?
Answer:-
To rename a shortcut:
*    Right-click the shortcut.
*    Click Rename.
*    Type the new name.


Question # 46
How to change the icon associated with an object?
Answer:-
To change the icon associated with an object:
*    Right-click the icon. The context menu will appear.
*    Click Properties.
*    Click the Change Icon button.
*    Click the icon of your choice.
*    Click OK.


Question # 47
How does desktop shortcut wizard work?
Answer:-
*    Right-click the desktop. The context menu will appear.
*    Click New. A sub-menu will appear.
*    Click Shortcut. The Create Shortcut dialog box will appear.


*    Type in the location and name of the item to which you want to create a shortcut. Alternatively, browse to find the item.
*    Click Next. A dialog box will appear.
*    Accept the default name or type in a new name.
*    Click Finish.


Question # 48
What is the mean of image to appear on center screen?
Answer:-
Place the image in the center of the screen.


Question # 49
What is the mean of image to appear on Tile screen?
Answer:-
Have the image display as tiles across and down the screen.


Question # 50
What is the mean of image to appear on Stretch screen?
Answer:-
Stretch the image so the image covers the entire screen.


Question # 51
What is font?
Answer:-
A font is a set of characters represented in a single typeface. Each character within a font is created by using the same basic style.


Question # 52
What is font size?
Answer:-
Fonts are measured in points. There are 72 points to an inch. The number of points assigned to a font is based on the distance from the top to the bottom of its longest character.


Question # 53
How to install a new font?
Answer:-
To install a new font:
*    Click the Start button.
*    Highlight Settings.
*    Click Control Panel.
*    Click Fonts. The Fonts window will open.
*    Click File, which is located on the menu bar.
*    Click Install New Font.
*    Specify the drive and folder where the font you want to install is currently located.
*    Select the font you want to install from the fonts listed in the List of Fonts box.
*    Select Copy Fonts to Fonts Folder (this will put a copy of the font you are installing in the Fonts folder).
*    Click OK.


Question # 54
What is the Character Map?
Answer:-
The Character Map displays the characters available in a selected font. To view the Character Map dialog box:
*    Click the Start button.
*    Highlight Programs.
*    Highlight Accessories.
*    Highlight System Tools.
*    Click Character Map.


Question # 55


What is wallpaper?
Answer:-
Wallpaper is the background that displays on your desktop.


Question # 56
How to change wallpaper?
Answer:-
To change your wallpaper:
*    Right-click your desktop.
*    Highlight Properties.
*    Click the Desktop tab.
*    Select the wallpaper you want from the list that appears in the Background box.


Question # 57
How Windows XP organize files and folders on drives?
Answer:-
Windows XP organizes folders and files in a hierarchical system. The drive is the highest level of the hierarchy. You can put all of your files on the drive without creating any folders, but that is like putting all of your papers in a file cabinet without organizing them into folders. It works fine if you have only a few files, but as the number of files increases, there comes a point at which things become very difficult to find. So you create folders and put related material together in folders.


Question # 58
How to create a new folder when in Windows Explorer?
Answer:-
To create a new folder:
*    In the left pane, click the drive or folder in which you want to create the new folder.
*    Click any free area in the right pane. A context menu will appear.
*    Highlight New.
*    Click Folder.
*    Type a name for the folder.


Question # 59
What are folders?
Answer:-
Folders are used to organize the data stored on your drives. The files that make up a program are stored together in their own set of folders. You will want to organize the files you create in folders. You will want to store files of a like kind in a single folder.


Question # 60
Explain the Windows Explorer window?
Answer:-
Windows XP separates the window into two panes. If you click an object in the left pane, the contents of the object display in the right pane. Click Desktop and the contents of the Desktop folder display on the right. Click My Computer and your computer resources display on the right. To see the contents of a drive, click the drive. To see the contents of a folder, click the icon for the folder in the left pane.


Question # 61
How to change the Windows Explorer views?
Answer:-
To change the view:
*    Right-click any free area in the right pane. A context menu will appear.
*    Highlight View.
*    Select the view you want from the drop-down menu.


Question # 62
Explain Windows Explorer views?
Answer:-
Yes. Views control how Windows Explorer displays information in the right pane. Windows Explorer provides you with the following choices: Thumbnails, Tiles, Icons, List, and Details.
*    Thumbnails view displays images. These images represent the contents of folders and files. For example, if a folder contains pictures, up to four of the pictures in the folder will be displayed on the folder icon.


*    Tiles view and Icons view display icons to represent drives, folders, and the contents of folders. The icons displayed when you choose Tiles view are larger than the icons that display when you choose Icon view.
*    List view displays all of the files and folders without supplying the size, type, or date modified.
*    Details view displays the size, type, and date modified.


Question # 63
How to cut a file or folder?
Answer:-
To cut a file or folder:
*    Right-click the file or folder you want to cut. A context menu will appear.
*    Click Cut. The file or folder should now be on the Clipboard. Note:
Cutting differs from deleting. When you cut a file, the file is placed on the Clipboard. When you delete a file, the file is sent to the Recycle Bin.


Question # 64
How to delete a file or folder?
Answer:-
To delete a file or folder:
*    Right-click the file or folder you want to delete. A context menu will appear.
*    Click Delete. Windows Explorer will ask, "Are sure you want to send this object to the recycle bin?"
*    Click Yes.


Question # 65
How to paste a file or folder?
Answer:-
To paste a file or folder:
*    After cutting or copying the file, right-click the object or right-click in the right pane of the folder to which you want to paste. A context menu will appear.
*    Click Paste.


Question # 66
How to copy a file or folder?
Answer:-
To copy a file or folder:
*    Right-click the file or folder you want to copy. A context menu will appear.
*    Click Copy. The file or folder should now be on the Clipboard.


Question # 67
How to rename a file or folder?
Answer:-
To rename a file or folder:
*    Right-click the file or folder. A context menu will appear.
*    Click Rename.
*    Type the new name.


Question # 68
What is screen saver?
Answer:-
Computer monitors display images by firing electron beams at a phosphor-coated screen. If the same image stays on the screen too long, there is a danger that the image will leave a permanent imprint on the screen. Screen savers help prevent this by providing a constantly changing image.


Question # 69
How to select a screen saver?
Answer:-
To select a screen saver:
*    Right-click anywhere on the Windows desktop. A context menu will appear.
*    Choose Properties. The Display Properties dialog box will appear.
*    Click the Screen Saver tab.
*    The Screen Saver field provides the list of available screen savers. Select the screen saver you want from the list.
*    Click Preview to preview your screen saver.


*    Click Esc to return to the Display Properties dialog box.
*    In the Wait field, set the number of minutes of inactivity before the screen saver starts.
*    Click OK.


Question # 70
Where are games?
Answer:-
Several games are included with Windows XP. To access the games:
*    Click the Start button, which is located in the lower left corner of the screen. The Start menu will appear.
*    Highlight Programs. A submenu will appear.
*    Highlight Games. Another submenu will appear.
*    Click the game you want to play.


Question # 71
What are drives?
Answer:-
Drives are used to store data. Almost all computers come with at least two drives: a hard drive (which is used to store large volumes of data) and a CD drive(which stores smaller volumes of data that can be easily transported from one computer to another). The hard drive is typically designated the C: drive and the CD drive is typically designated the D: drive. If you have an additional floppy drive, it is typically designated the A: drive. If your hard drive is partitioned or if you have additional drives, the letters E:, F:, G: and so on are assigned.

DBA Interview Questions

DBA Interview Questions with Answers


Can one switch to another database user without a password?
Users normally use the "CONNECT" statement to connect from one database user to another. However, DBAs can switch from one user to another without a password. Of course it is not advisable to bridge Oracle's security, but look at this example:
SQL> CONNECT / as sysdba
SQL> SELECT password FROM dba_users WHERE  username='SCOTT';
F894844C34402B67
SQL> ALTER USER scott IDENTIFIED BY anything;
SQL> CONNECT scott/anything
OK, we're in. Let's quickly change the password back before anybody notices.
SQL> ALTER USER scott IDENTIFIED BY VALUES 'F894844C34402B67';
User altered.
How do you delete duplicate rows in a table?
There is a several method to delete duplicate row from the table:
Method1:
DELETE FROM SHAAN A WHERE ROWID >
(SELECT min(rowid) FROM SHAAN B
WHERE A.EMPLOYEE_ID = B.EMPLOYEE_ID);
Method2:
delete from SHAAN t1
where  exists (select 'x' from SHAAN t2
where t2.EMPLOYEE_ID = t1.EMPLOYEE_ID
and t2.EMPLOYEE_ID = t1.EMPLOYEE_ID
and t2.rowid      > t1.rowid);
Method3:
DELETE SHAAN
WHERE  rowid IN
( SELECT LEAD(rowid) OVER
(PARTITION BY EMPLOYEE_ID ORDER BY NULL)
FROM   SHAAN );
Method4:
delete from SHAAN where rowid not in
( select min(rowid)
from SHAAN group by EMPLOYEE_ID);
Method5:
delete from SHAAN
where rowid not in ( select min(rowid)
from SHAAN group by EMPLOYEE_ID);
Method6:
SQL> create table table_name2 as select distinct * from table_name1;
SQL> drop table table_name1;
SQL> rename table_name2 to table_name1;
What is Automatic Management of Segment Space setting?
Automatic Segment Space Management (ASSM) introduced in Oracle9i is an easier way of managing space in a segment using bitmaps. It eliminates the DBA from setting the parameters pctused, freelists, and freelist groups.
ASSM can be specified only with the locally managed tablespaces (LMT). The CREATE TABLESPACE statement has a new clause SEGMENT SPACE MANAGEMENT. Oracle uses bitmaps to manage the free space. A bitmap, in this case, is a map that describes the status of each data block within a segment with respect to the amount of space in the block available for inserting rows. As more or less space becomes available in a data block, its new state is reflected in the bitmap.
CREATE TABLESPACE myts DATAFILE '/oradata/mysid/myts01.dbf' SIZE 100M
EXTENT MANAGEMENT LOCAL UNIFORM SIZE 2M
SEGMENT SPACE MANAGEMENT AUTO;

What is COMPRESS and CONSISTENT setting in EXPORT utility?
If COMPRESS=Y, the INITIAL storage parameter is set to the total size of all extents allocated for the object. The change takes effect only when the object is imported.
Setting CONSISTENT=Y exports all tables and references in a consistent state. This slows the export, as rollback space is used. If CONSISTENT=N and a record is modified during the export, the data will become inconsistent.
What is the difference between Direct Path and Convention Path loading?
When you use SQL loader by default it use conventional path to load data. This method competes equally with all other oracle processes for buffer resources. This can slow the load. A direct path load eliminates much of the Oracle database overhead by formatting Oracle data blocks and writing the data blocks directly to the database files. If load speed is most important to you, you should use direct path load because it is faster.
What is an Index Organized Table?
An index-organized table (IOT) is a type of table that stores data in a B*Tree index structure. Normal relational tables, called heap-organized tables, store rows in any order (unsorted).
CREATE TABLE my_iot (id INTEGER PRIMARY KEY, value VARCHAR2 (50)) ORGANIZATION INDEX;
What are a Global Index and Local Index?
When you create a partitioned table, you should create an index on the table. The index may be partitioned according to the same range values that were used to partition the table. Local keyword in the index partition tells oracle to create a separate index for each partition of the table. TheGlobal clause in create index command allows you to create a non-partitioned index or to specify ranges for the index values that are different from the ranges for the table partitions. Local indexes may be easier to manage than global indexes however, global indexes may perform uniqueness checks faster than local (portioned) indexes perform them.
What is difference between Multithreaded/Shared Server and Dedicated Server?
Oracle Database creates server processes to handle the requests of user processes connected to an instance.dedicated server process, which services only one user processshared server process, which can service multiple user processes
Your database is always enabled to allow dedicated server processes, but you must specifically configure and enable shared server by setting one or more initialization parameters.
Can you import objects from Oracle ver. 7.3 to 9i?
We can not import from lower version export to higher version in fact. But not sure may be now concept is changed.
How do you move tables from one tablespace to another tablespace?
Method 1:
Export the table, drop the table, create the table definition in the new tablespace, and then import the data (imp ignore=y).
Method 2:
Create a new table in the new tablespace with the "CREATE TABLE x AS SELECT * from y" command:
CREATE TABLE temp_name TABLESPACE new_tablespace AS SELECT * FROM real_table;
Then drop the original table and rename the temporary table as the original:
DROP TABLE real_table;
RENAME temp_name TO real_table;
Note: After step #1 or #2 is done, be sure to recompile any procedures that may have been
invalidated by dropping the table. Prefer method #1, but #2 is easier if there are no indexes, constraints, or triggers. If there are, you must manually recreate them.
Method 3:
If you are using Oracle 8i or above then simply use:
SQL>Alter table table_name move tablespace tablespace_name;

How do see how much space is used and free in a tablespace?
SELECT * FROM SM$TS_FREE;
SELECT TABLESPACE_NAME, SUM(BYTES) FROM DBA_FREE_SPACE GROUP BY TABLESPACE_NAME;
Can view be the based on other view?
Yes, the view can be created from other view by directing a select query to use the other view data.
What happens, if you not specify Dictionary option with the start option in case of LogMinor concept?
It is recommended that you specify a dictionary option. If you do not, LogMiner cannot translate internal object identifiers and datatypes to object names and external data formats. Therefore, it would return internal object IDs and present data as hex bytes. Additionally, the MINE_VALUE andCOLUMN_PRESENT functions cannot be used without a dictionary.

What is the Benefit and draw back of Continuous Mining?

The continuous mining option is useful if you are mining in the same instance that is generating the redo logs. When you plan to use the continuous mining option, you only need to specify one archived redo log before starting LogMiner. Then, when you start LogMiner specify theDBMS_LOGMNR.CONTINUOUS_MINE option, which directs LogMiner to automatically add and mine subsequent archived redo logs and also the online catalog.
Continuous Mining is not available in Real Application Cluster.
What is LogMiner and its Benefit?
LogMiner is a recovery utility. You can use it to recover the data from oracle redo log and archive log file. The Oracle LogMiner utility enables you to query redo logs through a SQL interface. Redo logs contain information about the history of activity on a database.
Benefit of LogMiner?
1.  Pinpointing when a logical corruption to a database; suppose when a row is accidentally deleted then logMiner helps to recover the database exact time based and changed based recovery.
2.  Perform table specific undo operation to return the table to its original state. LogMiner reconstruct the SQL statement in reverse order from which they are executed.
3.  It helps in performance tuning and capacity planning. You can determine which table gets the most update and insert. That information provides a historical perspective on disk access statistics, which can be used for tuning purpose.
4.  Performing post auditing; LogMiner is used to track any DML and DDL performed on database in the order they were executed.
What is Oracle DataGuard?
Oracle DataGuard is a tools that provides data protection and ensures disaster recovery for enterprise data. It provides comprehensive set of services that create, maintain, manage, and monitor one or more standby databases to enable production Oracle databases to survive disasters and data corruption. Dataguard maintains these standsby databases as transitionally consistent copies of the production database. Then, if the production database becomes failure Data Guard can switch any standby database to the production role, minimizing the downtime associated with the outage. Data Guard can be used with traditional backup, restoration, and cluster techniques to provide a high level of data protection and data availability.
What is Standby Databases
A standby database is a transitionally consistent copy of the primary database. Using a backup copy of the primary database, you can create up to9 standby databases and incorporate them in a Data Guard configuration. Once created, Data Guard automatically maintains each standby database by transmitting redo data from the primary database and then applying the redo to the standby database.
Similar to a primary database, a standby database can be either a single-instance Oracle database or an Oracle Real Application Clusters database. A standby database can be either a physical standby database or a logical standby database:
Difference between Physical standby Logical standby databases
Provides a physically identical copy of the primary database on a block-for-block basis. The database schema, including indexes, is the same. A physical standby database is kept synchronized with the primary database, though Redo Apply, which recovers the redo data, received from the primary database and applies the redo to the physical standby database.
Logical Standby database contains the same logical information as the production database, although the physical organization and structure of the data can be different. The logical standby database is kept synchronized with the primary database though SQL Apply, which transforms the data in the redo received from the primary database into SQL statements and then executing the SQL statements on the standby database.
If you are going to setup standby database what will be your Choice Logical or Physical?
We need to keep the physical standby database in “recovery mode” in order to apply the received archive logs from the primary database. We can open “physical stand by database to “read only” and make it available to the applications users (Only select is allowed during this period). Once the database is opened in “Read only” mode then we can not apply redo logs received from primary database.
We do not see such issues with logical standby database. We can open up the database in normal mode and make it available to the users. At the same time, we can apply archived logs received from primary database.
If the primary database needed to support pretty large user community for the OLTP system and pretty large “Reporting Group” then better to uselogical standby as primary database instead of physical database.
What are the requirements needed before preparing standby database?
·   OS Architecture of primary database secondary database should be same.
·   The version of secondary database must be the same as primary database.
·   The Primary database must run in Archivelog mode.
·   Require the same hardware architecture on the primary and all standby site.
·   Does not require the same OS version and release on the primary and secondary site.
·   Each Primary and secondary database must have its own database.
What are “Failover” and “Switchover” in case of dataguard?
Failover is the operation of bringing one of the standby databases online as the new primary database when failure occurs on the primary database and there is no possibility of recover primary database in a timely manner. The switchover is a situation to handle planned maintenance on the primary database. The main difference between switchover operation and failover operation is that switchover is performed when primary database is still available or it does not require a flash back or re-installation of the original primary database. This allows the original primary database to the role of standby database almost immediately. As a result schedule maintenance can performed more easily and frequently.
When you use WHERE clause and when you use HAVING clause?
HAVING clause is used when you want to specify a condition for a group function and it is written after GROUP BY clause The WHERE clause is used when you want to specify a condition for columns, single row functions except group functions and it is written before GROUP BY clause if it is used.
What is a cursor and difference between an implicit & an explicit cursor?
A cursor is a PL/SQL block used to fetch more than one row in a Pl/SQl block. PL/SQL declares a cursor implicitly for all SQL data manipulation statements, including quries that return only one row. However, queries that return more than one row you must declare an explicit cursor or use a cursor FOR loop.
Explicit cursor is a cursor in which the cursor name is explicitly assigned to a SELECT statement via the CURSOR...IS statement. An implicit cursor is used for all SQL statements Declare, Open, Fetch, Close. An explicit cursors are used to process multirow SELECT statements An implicit cursor is used to process INSERT, UPDATE, DELETE and single row SELECT. .INTO statements.

Explain the difference between a data block, an extent and a segment.A data block is the smallest unit of logical storage for a database object. As objects grow they take chunks of additional storage that are composed of contiguous data blocks. These groupings of contiguous data blocks are called extents. All the extents that an object takes when grouped together are considered the segment of the database object.
You have just had to restore from backup and do not have any control files. How would you go about bringing up this database?I would create a text based backup control file, stipulating where on disk all the data files where and then issue the recover command with the using backup control file clause.
A table is classified as a parent table and you want to drop and re-create it. How would you do this without affecting the children tables?Disable the foreign key constraint to the parent, drop the table, re-create the table, and enable the foreign key constraint.
How to Unregister database from Rman catalog
First we start up RMAN with a connection to the catalog and the target, making a note of the DBID in the banner:
C:\>rman catalog=rman/rman@shaan target=HRMS/password@orcl3
connected to target database: W2K1 (DBID=691421794)
connected to recovery catalog database
Note the DBID from here. Next we list and delete any backupset recorded in the repository:
RMAN> LIST BACKUP SUMMARY;
RMAN> DELETE BACKUP DEVICE TYPE SBT;
RMAN> DELETE BACKUP DEVICE TYPE DISK;
Next we connect to the RMAN catalog owner using SQL*Plus and issue the following statement:
SQL> CONNECT rman/rman@shaan
SQL> SELECT db_key, db_id  FROM   db
                WHERE  db_id = 1487421514;
                DB_KEY                DB_ID
----------                   ----------
                1                              691421794
The resulting key and id can then be used to unregister the database:
SQL> EXECUTE dbms_rcvcat.unregisterdatabase(1, 691421794);
PL/SQL procedure successfully completed.

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