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Database Management Systems

5,344 Questions

Database Management Systems (DBMS) form the core framework for data storage, retrieval, and security in modern software applications. Concepts such as the E-R model, backup planning, SQL integration, and big data architecture are essential for computer knowledge sections. This hub offers a comprehensive set of practice questions to master DBMS fundamentals and advanced database operations.

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Database Management Systems Questions

Multiple choice technology databases

What file will give you Oracle instance status information?

  1. alert.ora

  2. init.ora

  3. tnsname.ora

  4. redolog
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The alert log (often historically referred to or associated with alert.log or an alert file) contains critical status and error information for the Oracle instance. The init.ora is for parameters, tnsnames.ora is for Net configuration, and redologs store change vectors.

Multiple choice technology databases

Which three attributes of the LOG_ARCHIVE_DEST_n initialization parameter control the data availability mode of a Data Guard standby database? (Choose three)

  1. SYNC or ASYNC to identify the network transmission mode.

  2. LGWR or ARCH to identify the primary database process responsible for sending redo information to the standby.

  3. AFFIRM or NOAFFIRM to control whether log archiving disk write operations are to be performed synchronously or asynchronously.

  4. PROTECTED or UNPROTECTED to control the degree of divergence and data loss at the standby database.
Reveal answer Fill a bubble to check yourself
A Correct answer
Multiple choice technology databases

CREATE TABLESPACE user_data DATAFILE '/u01/oradata/user_data_01.dbf' SIZE 100M LOCALLY MANAGED UNIFORM SIZE 1M AUTOMATIC SEGMENT SPACE MANAGEMENT; Which part of the tablespace will be of a uniform size of 1 MB?

  1. Extent

  2. Segement

  3. Oracle block

  4. Operating system block
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The UNIFORM SIZE 1M clause sets the extent size to 1 MB uniformly across the tablespace. Each extent allocated will be exactly 1 MB, not the segment, block, or OS block. SEGMENT is the collection of extents. Oracle block is the smallest unit of I/O (typically 8KB). OS block is managed by the operating system.

Multiple choice technology databases

What should you look at to compute the number of undo blocks written per second on disk ?
  1. V$UNDOSTAT
  2. V$TRANSACTION
  3. V$ROLLSTAT

  4. DBA_UNDO_EXTENTS

  5. DBA_ROLLBACK_SEGS
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

V$UNDOSTAT provides undo statistics including undo blocks written, which can be used to calculate blocks per second. It tracks undo usage over time intervals. V$TRANSACTION shows current transactions but not historical rates. V$ROLLSTAT shows rollback segment statistics but not per-second rates. DBA_UNDO_EXTENTS shows extent allocation, not write rates. DBA_ROLLBACK_SEGS shows rollback segment configuration, not activity.

Multiple choice technology databases

When performing recovery of a database in NOARCHIVELOG mode with RMAN, the target database must be in the ______ state to restore the control file.

  1. OPEN

  2. IDLE

  3. MOUNT

  4. NOMOUNT
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

To restore the control file using RMAN, the target database must be in a NOMOUNT state because the control file itself is required to transition the database to the MOUNT state. OPEN and MOUNT require the control file to already be loaded.

Multiple choice technology databases

An Oracle instance is executing in a nondistributed configuration. The instance fails because of an operating system failure. Which background process would perform the instance recovery when the atabase is reopened ?

  1. PMON

  2. SMON

  3. RECO

  4. ARCn

  5. CKPT
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

SMON (System Monitor) performs instance recovery after a crash, including rolling forward uncommitted changes and rolling back uncommitted transactions. PMON (Process Monitor) cleans up failed processes. RECO handles distributed transaction recovery. ARCn archives redo logs. CKPT (Checkpoint) updates file headers to checkpoint position.

Multiple choice technology databases

You want to drop the TBSI tablespace from your database. You also want to delete corresponding data files automatically, and not have to do it manually. What should you do ?

  1. User the DROP DATAFILE command.

  2. Use the DROP TABLESPACE command.

  3. Ensure that all database files are Oracle Managed Files(OMF) before using the DROP TABLESPACE command.

  4. Ensure that the DB_FILE_CREATE_DEST initialization parameter is set before using the DROP TABLESPACE command.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The DROP TABLESPACE command is used to remove a tablespace from the database. To automatically delete the associated data files, you must include the INCLUDING CONTENTS AND DATAFILES clause. Option A mentions a non-existent DROP DATAFILE command, while options C and D describe prerequisites for automatic file deletion in Oracle Managed Files environments.

Multiple choice technology databases

The ORDERS table has a constant transaction load 24 hours a day, so down time is not allowed. The index become fragmented. Whic statment is true ?

  1. The index need to be dropped, and then re-created.

  2. The resolution of index fragmentation depends on the type of index.

  3. The index can be rebuilt while users continue working on the table.

  4. The fragmented can be ignored because Oracle resolve index fragmentation by means of a freelist.

  5. The index can be rebuilt, but users will not have access to the index during this time.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Oracle allows online index rebuilds using the ALTER INDEX ... REBUILD ONLINE command. This operation rebuilds the fragmented index while maintaining DML operations on the underlying table. Dropping and recreating the index (option A) would work but causes more downtime. Option E is incorrect because users can continue working during an online rebuild. The fragmentation type (option B) doesn't determine whether you can rebuild online.

Multiple choice technology databases

You omit the UNDO tablespace clause in your CREATE DATABASE statment. The UNDO_MANAGEMENT parameter is set to AUTO. What is the result of your CREATE DATABASE statement ?

  1. The oracle server creates no undo tablespace.

  2. The oracle server creates an undo segment in the system tablespace.

  3. The oracle server cerates one undo tablespace with the name SYS_UNDOTBS.

  4. Database creation fails because you did not specify an undo tablespace on the create database statment.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

If UNDO_MANAGEMENT is set to AUTO and the UNDO tablespace clause is omitted in the CREATE DATABASE statement, Oracle automatically creates a default undo tablespace named SYS_UNDOTBS. It does not fail, create no tablespace, or put undo in SYSTEM.

Multiple choice technology databases

John has created a procedure named SALARY_CALC. Which SQL query allow him to view text of procedure?

  1. SELECT text FROM user_source WHERE name = 'SALARY_CALC';

  2. SELECT * FROM user_source WHERE name='SALARY_CALC';

  3. SELECT * FROM user_objects WHERE object_name='SALARY_CALC';

  4. SELECT * FROM user_procedures WHERE object_name='SALARY_CALC';

  5. SELECT text FROM user_source WHERE name='SALARY_CALC' and owner='JOHN'
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The correct SQL query to view the text of the procedure named SALARY_CALC, created by John, would be:

A. SELECT text FROM user_source WHERE name = 'SALARY_CALC';

This query selects the text column from the user_source table where the name is equal to 'SALARY_CALC'. This will retrieve the text of the procedure.

The other options are incorrect because:

B. SELECT * FROM user_source WHERE name='SALARY_CALC'; This query selects all columns from the user_source table where the name is equal to 'SALARY_CALC'. It will retrieve all details of the procedure, not just the text.

C. SELECT * FROM user_objects WHERE object_name='SALARY_CALC'; This query selects all columns from the user_objects table where the object_name is equal to 'SALARY_CALC'. This will retrieve details about the object, but not the text of the procedure.

D. SELECT * FROM user_procedures WHERE object_name='SALARY_CALC'; This query selects all columns from the user_procedures table where the object_name is equal to 'SALARY_CALC'. This will retrieve details about the procedure, but not the text of the procedure.

E. SELECT text FROM user_source WHERE name='SALARY_CALC' and owner='JOHN'; This query selects the text column from the user_source table where the name is equal to 'SALARY_CALC' and the owner is equal to 'JOHN'. This query assumes that John is the owner of the procedure. If John is indeed the owner, this query will work. However, if John is not the owner, it will not retrieve the text of the procedure.

So, the correct answer is option A.

Multiple choice technology databases

The employees table is stored in the SAMPLE tablespace. The corresponding IPK_EMP index for the EMPLOYEES table's primary key is stored in INDX tablespace. Out of 12 partitions, only partition P1 of the SALES table is stored in the SAMPLE tablespace. Which object will be exported by this command ? exp system/manager tablespace=SAMPLE

  1. Only the EMPLOYEES table.

  2. Only the EMPLOYEES table and its corresponding primary key index.

  3. The EMPLOYEES table and partition P1.

  4. The EMPLOYEES table, IPK_EMP index, and the SALES table.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

When you export by tablespace using exp with tablespace=SAMPLE, Oracle exports all database segments stored in that tablespace. This includes tables, indexes, and partitions. The SAMPLE tablespace contains the EMPLOYEES table and its primary key index IPK_EMP (stored separately in INDX but associated with EMPLOYEES). Partition P1 of SALES is also in SAMPLE, so the entire SALES table definition is exported (though only P1's data is in SAMPLE).

Multiple choice technology databases

When performing an incomplete recovery of the whole database, what must be true about the data files that are restored ?

  1. All of the data files must be from a backup taken prior to the point in time to which you want to recover.

  2. Only the data files belonging from the SYSTEM tablespace must be from a backup taken prior to the point in time to which you want to recover.

  3. Only the data files that need recovery must be from a backup taken prior to the point in time which you want to recover.

  4. Only the data files belonging to the SYSTEM tablespace and the data files that need recovery must be from a backup taken prior to the point in time to which you want to recover.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

For incomplete recovery, the entire database must be restored to a consistent state prior to the target time. Thus, all restored data files must originate from backups taken before the point-in-time target. Restoring only SYSTEM or a subset of files prevents full consistency.

Multiple choice technology databases

You have performed the first step in placing your database into ARCHIVELOG mode. The second step is deciding whether the online redo log files are to be archived automatically or manually. which action should you take to enable archiving an instance startup?

  1. Set the LOG_ARCHIVE_START parameter to TRUE in the initialization parameter file.

  2. Automatic archive is the default when ARCHIVELOG mode is set. No further actions are required.

  3. Set the LOG_ARCHIVE_MAX_PROCESSES parameter to n (where n is the number of Archiver process) in the initialization parameter file.

  4. Immediately after setting the database in ARCHIVELOG mode, in SQL*Plus select automatic archiving using the syntax : ALTER DATABASE SET LOG_ARCHIVE_START=TRUE
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The LOG_ARCHIVE_START initialization parameter controls automatic archiving of redo log files. Setting it to TRUE in the parameter file enables automatic archiving when the instance starts. Automatic archiving is not the default (option B). LOG_ARCHIVE_MAX_PROCESSES (option C) controls the number of archiver processes, not whether archiving is enabled. Option D incorrectly tries to set LOG_ARCHIVE_START with ALTER DATABASE.