Computer Knowledge

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

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

To enable automatic archiving of redo logs, set LOG_ARCHIVE_START=TRUE in the initialization parameter file. This causes the ARCH process to automatically archive filled redo logs. Option B is incorrect - automatic archiving is not the default. Option C controls the number of archiver processes but doesn't enable automatic archiving. Option D has incorrect syntax - this is a parameter, not an ALTER DATABASE option.

Multiple choice technology databases

You issue this statement ALTER DATABASE BACKUP CONTROLFILE TO TRACE; What does the statment generate ?

  1. A text copy of the control file.

  2. A binary copy of the control file.

  3. A file containing a SQL statement which will re-create the database.

  4. A file containing a SQL statement which will re-create the control file.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The ALTER DATABASE BACKUP CONTROLFILE TO TRACE command generates a trace file in the user_dump_dest directory containing SQL statements (CREATE CONTROLFILE) that can be used to recreate the control file. Option A is incorrect - it's not a direct copy. Option B describes binary control file backups. Option C is wrong - it recreates the control file, not the entire database. This is useful for recovery or control file reconstruction.

Multiple choice technology databases

Which statement is true regarding RMAN components?

  1. Each target database requires its own recover catalog.

  2. RMAN scripts can be stored in the recovery catalog or the targer control file.

  3. A channel is a stream of data to a device type and corresponds to one server session.

  4. The RMAN executable interprets server session commands and establishes connections to the target database.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

An RMAN channel represents a single stream of data to a backup device and corresponds to one active server session on the target database instance.

Multiple choice technology databases

Which statement is ture regarding checkpoints and recovery ?

  1. A checkpoint defines the highest system change number (SCN)

  2. All redo entries higher or at the SCN are known to be written to the data files.

  3. Only the redo records containing SCNs higher then the checkpoint need to be applied during recovery.

  4. The LOG_CHECKPOINT_INTERVAL initialization paramter specifies the amount of time beteen incremental checkpoints.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

An Oracle checkpoint marks the highest system change number (SCN) guaranteed to be written to data files. During recovery, only redo records containing SCNs higher than the checkpoint need to be applied because all changes at or below the checkpoint are already safely on disk.

Multiple choice technology databases

Examine the statement : DROP TABLESPACE IND2 INCLUDING CONTENTS AND DATAFILES; What is the result of the statement?

  1. The contents and data files belonging to the IND2 tablespace are dropped.

  2. The statement will only succeed if the IND2 tablespace was built using Oracle-Managed Files (OMF) data files.

  3. The statement will only succeed if the data files belonging to the IND2 tablespace are Oracle Managed Files (OMF) or of the database was created using OMF.

  4. The contents of the tablespace are dropped along with all its data files except those identical with Oracle-Managed Files (OMF) naming convention.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The 'INCLUDING CONTENTS AND DATAFILES' clause drops the tablespace, its schema objects, and deletes the associated physical operating system data files, regardless of whether they are Oracle-Managed Files.

Multiple choice technology databases

A user is running a long update batch file. Many tables are updated and all the statements are in one transaction. Before the process is finished, the user machine lost power. When the user calls you, what should you do as DBA?

  1. Do nothing, the PMON process handles everything.

  2. Shut down the database and restore all the tables the user was updating.

  3. Log in as DBA, clean up the partial updates in those tables, and do another manual backup.

  4. Use LogMiner to find out which records are changed based on the user’s ID, then roll back all those changes.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

PMON (Process Monitor) is the background process responsible for cleaning up failed user processes and rolling back their uncommitted transactions. When the client machine loses power mid-transaction, PMON automatically detects and rolls back the incomplete transaction when the instance remains available.

Multiple choice technology databases

Your database is running in NOARCHIVELOG mode. Every night there is a backup taken using RMAN. During your startup this morning you received an error regarding DISK 3 on your server.This is the location of your data file for the SYSTEM tablespace. Which option is open to you?

  1. The data file needs to be restored by using operating system commands, because a data file movement must take place, and then the database can be recovered from RMAN.

  2. The data file needs to be restored by using operating system commands, since a data file movement must take place, and then the database must be recovered manually.

  3. From RMAN you can issue the commands RESTORE and RECOVER. RMAN automatically restores the data file on DISK 3 to another disk, based upon utilization statistics.

  4. From RMAN you can issue a SET NEWNAME command to update the data file location information in the control file, and then issue the RESTORE and RECOVER commands to recover the database.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

In NOARCHIVELOG mode, when a data file is lost, RMAN can restore it to a new location using SET NEWNAME to update the control file metadata, then RESTORE to copy from backup and RECOVER to apply available redo. This is necessary because DISK 3 failed and the file must be restored elsewhere.

Multiple choice technology databases

Consider this RMAN command: RMAN> CONFIGURE RETENTION POLICY CLEAR; What is the effect of this command?

  1. Backups will never expire.

  2. It removes any retention policy.

  3. The DELETE OBSOLETE command will fail with an error.

  4. It sets the retention policy to the default of REDUNDANCY 1.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

CONFIGURE RETENTION POLICY CLEAR resets the retention policy to its default setting, which is REDUNDANCY 1. This means RMAN will retain one backup of each file and consider older backups of the same file as obsolete.

Multiple choice technology databases

You have just run this syntax to start the listener from the Listener Control utility: LSNRCTL>START Starting /mstgelai/oracle/bin/tnslsnr: please wait... System parameter file is /u01/oracle/network/admin/listener.ora Log messages written to /u01/oracle/network/log/listener.log Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=stc-sun01-server)(PORT=1521))) Connecting to... The command completed successfully What is the name of the Listener you started?

  1. TNSLSNR

  2. LISTENER

  3. LOCAL_LISTENER

  4. DEFAULT_LSRN
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When starting the listener using the command 'START' without specifying a name, the Listener Control utility defaults to starting the listener named 'LISTENER'.

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 when an Oracle instance restarts after a failure. In a nondistributed configuration, SMON rolls forward changes in the online redo log and rolls back uncommitted transactions to bring the database to a consistent state.

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 supports online index rebuild using ALTER INDEX ... REBUILD ONLINE, which allows the index to be rebuilt while users continue to access the table. You don't need to drop and recreate the index. While fragmentation resolution does depend on index type, the key capability for 24/7 systems is online rebuild.