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Computer Interview Questions Answers

Oracle Interview Questions Answers

Question - 151 : - Describe two phases of Two-phase commit ?

Answer - 151 : - Prepare phase - The global coordinator (initiating node) ask a participants to prepare (to promise to commit or rollback the transaction, even if there is a failure) Commit - Phase - If all participants respond to the coordinator that they are prepared, the coordinator asks all nodes to commit the transaction, if all participants cannot prepare, the coordinator asks all nodes to roll back the transaction.

Question - 152 : - What are the different modals of windows?

Answer - 152 : - Modalless windows Modal windows

Question - 153 : - How can a square be drawn in the layout editor of the report writer?

Answer - 153 : - By using the rectangle tool while pressing the (Constraint) key.

Question - 154 : - What use of command line parameter cmd file?

Answer - 154 : - It is a command line argument that allows you to specify a file that contain a set of arguments for r20run.

Question - 155 : - What is the remove on exit property?

Answer - 155 : - For a modelless window, it determines whether oracle forms hides the window automatically when the operators navigates to an item in the another window.

Question - 156 : - Why and when should one tune? (for DBA)

Answer - 156 : - One of the biggest responsibilities of a DBA is to ensure that the Oracle database is tuned properly. The Oracle RDBMS is highly tunable and allows the database to be monitored and adjusted to increase its performance. One should do performance tuning for the following reasons: The speed of computing might be wasting valuable human time (users waiting for response); Enable your system to keep-up with the speed business is conducted; and Optimize hardware usage to save money (companies are spending millions on hardware). Although this FAQ is not overly concerned with hardware issues, one needs to remember than you cannot tune a Buick into a Ferrari.

Question - 157 : - How does one backup a database using RMAN?

Answer - 157 : - The biggest advantage of RMAN is that it only backup used space in the database. Rman doesn't put tablespaces in backup mode, saving on redo generation overhead. RMAN will re-read database blocks until it gets a consistent image of it. Look at this simple backup example. rman target sys/*** nocatalog run { allocate channel t1 type disk; backup format '/app/oracle/db_backup/%d_t%t_s%s_p%p' ( database ); release channel t1; } Example RMAN restore: rman target sys/*** nocatalog run { allocate channel t1 type disk; # set until time 'Aug 07 2000 :51'; restore tablespace users; recover tablespace users; release channel t1; } The examples above are extremely simplistic and only useful for illustrating basic concepts. By default Oracle uses the database controlfiles to store information about backups. Normally one would rather setup a RMAN catalog database to store RMAN metadata in. Read the Oracle Backup and Recovery Guide before implementing any RMAN backups. Note: RMAN cannot write image copies directly to tape. One needs to use a third-party media manager that integrates with RMAN to backup directly to tape. Alternatively one can backup to disk and then manually copy the backups to tape.

Question - 158 : - What is a data segment?

Answer - 158 : - Data segment are the physical areas within a database block in which the data associated with tables and clusters are stored.

Question - 159 : - How can we specify the Archived log file name format and destination?

Answer - 159 : - By setting the following values in init.ora file. LOG_ARCHIVE_FORMAT = arch %S/s/T/tarc (%S - Log sequence number and is zero left paded, %s - Log sequence number not padded. %T - Thread number lef-zero-paded and %t - Thread number not padded). The file name created is arch 0001 are if %S is used. LOG_ARCHIVE_DEST = path.

Question - 160 : - What is an Oracle view?

Answer - 160 : - A view is a virtual table. Every view has a query attached to it. (The query is a SELECT statement that identifies the columns and rows of the table(s) the view uses.)

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