McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Computer Science Engineering (CSE) , Bachelor of Science in Computer Science FY (BSc CS) , Bachelor of Science in Computer Science SY (BSc CS) , Bachelor of Science in Information Technology SY (BSc IT) , Bachelor of Computer Applications (BCA) .
Chapters
| 651. |
In concurrency control policy the lock is obtained on |
| A. | entire database |
| B. | a particular transaction alone |
| C. | all the new elements |
| D. | all of the mentioned |
| Answer» A. entire database | |
| 652. |
A concurrency-control policy such as this one leads to performance since it forces transactions to wait for preceding transactions to finish before they can start. |
| A. | good |
| B. | average |
| C. | poor |
| D. | unstable |
| Answer» C. poor | |
| 653. |
are used to ensure that transactions access each data item in order of the transactions’ if their accesses conflict. |
| A. | zone |
| B. | relay |
| C. | line |
| D. | timestamps |
| Answer» D. timestamps | |
| 654. |
In which scenario would you use the ROLLUP operator for expression or columns within a GROUP BY clause? |
| A. | to find the groups forming the subtotal in a row |
| B. | to create group-wise grand totals for the groups specified within a group by clause |
| C. | to create a grouping for expressions or columns specified within a group by clause in one direction, from right to left for calculating the subtotals |
| D. | to create a grouping for expressions or columns specified within a group by clause in all possible directions, which is cross- tabular report for calculating the subtotals |
| Answer» C. to create a grouping for expressions or columns specified within a group by clause in one direction, from right to left for calculating the subtotals | |
| 655. |
Which statement is true regarding external tables? |
| A. | the default reject limit for external tables is unlimited |
| B. | the data and metadata for an external table are stored outside the database |
| C. | oracle_loader and oracle_datapump have exactly the same functionality when used with an external table |
| D. | the create table as select statement can be used to unload data into regular table in the database from an external table |
| Answer» D. the create table as select statement can be used to unload data into regular table in the database from an external table | |
| 656. |
SNAPSHOT is used for (DBA) |
| A. | synonym |
| B. | tablespace |
| C. | system server |
| D. | dynamic data replication |
| Answer» D. dynamic data replication | |
| 657. |
Isolation of the transactions is ensured by |
| A. | transaction management |
| B. | application programmer |
| C. | concurrency control |
| D. | recovery management |
| Answer» C. concurrency control | |
| 658. |
Which of the following statements is/are not true for SQL profiler? |
| A. | enables you to monitor events |
| B. | check if rows are being inserted properly |
| C. | check the performance of a stored procedure |
| D. | all of the mentioned |
| Answer» C. check the performance of a stored procedure | |
| 659. |
Which of the following is the original purpose of SQL? |
| A. | to specify the syntax and semantics of sql data definition language |
| B. | to specify the syntax and semantics of sql manipulation language |
| C. | to define the data structures |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 660. |
SQL can be used to: |
| A. | create database structures only |
| B. | query database data only |
| C. | modify database data only |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 661. |
A lock that allows concurrent transactions to access different rows of the same table is known as a |
| A. | database-level lock |
| B. | table-level lock |
| C. | page-level lock |
| D. | row-level lock |
| Answer» D. row-level lock | |
| 662. |
Which of the following are introduced to reduce the overheads caused by the log- based recovery? |
| A. | checkpoints |
| B. | indices |
| C. | deadlocks |
| D. | locks |
| Answer» A. checkpoints | |
| 663. |
Which of the following protocols ensures conflict serializability and safety from deadlocks? |
| A. | two-phase locking protocol |
| B. | time-stamp ordering protocol |
| C. | graph based protocol |
| D. | none of the mentioned |
| Answer» B. time-stamp ordering protocol | |
| 664. |
Which refers to a property of computer to run several operation simultaneously and possible as computers await response of each other |
| A. | concurrency |
| B. | deadlock |
| C. | backup |
| D. | recovery |
| Answer» A. concurrency | |
| 665. |
The lock allows concurrent transactions to access the same row as long as they require the use of different fields within that row. |
| A. | table-level |
| B. | page-level |
| C. | row-level |
| D. | field-level |
| Answer» D. field-level | |
| 666. |
Which of the following is a procedure for acquiring the necessary locks for a transaction where all necessary locks are acquired before any are released? |
| A. | record controller |
| B. | exclusive lock |
| C. | authorization rule |
| D. | two phase lock |
| Answer» D. two phase lock | |
| 667. |
A system is in a state if there exists a set of transactions such that every transaction in the set is waiting for another transaction in the set. |
| A. | idle |
| B. | waiting |
| C. | deadlock |
| D. | ready |
| Answer» C. deadlock | |
| 668. |
The deadlock state can be changed back to stable state by using statement. |
| A. | commit |
| B. | rollback |
| C. | savepoint |
| D. | deadlock |
| Answer» B. rollback | |
| 669. |
What are the ways of dealing with deadlock? |
| A. | deadlock prevention |
| B. | deadlock recovery |
| C. | deadlock detection |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 670. |
When transaction Ti requests a data item currently held by Tj, Ti is allowed to wait only if it has a timestamp smaller than that of Tj (that is, Ti is older than Tj). Otherwise, Ti is rolled back (dies). This is |
| A. | wait-die |
| B. | wait-wound |
| C. | wound-wait |
| D. | wait |
| Answer» A. wait-die | |
| 671. |
When transaction Ti requests a data item currently held by Tj, Ti is allowed to wait only if it has a timestamp larger than that of Tj (that is, Ti is younger than Tj ). Otherwise, Tj is rolled back (Tj is wounded by Ti). This is |
| A. | wait-die |
| B. | wait-wound |
| C. | wound-wait |
| D. | wait |
| Answer» C. wound-wait | |
| 672. |
The situation where the lock waits only for a specified amount of time for another lock to be released is |
| A. | lock timeout |
| B. | wait-wound |
| C. | timeout |
| D. | wait |
| Answer» A. lock timeout | |
| 673. |
The deadlock in a set of a transaction can be determined by |
| A. | read-only graph |
| B. | wait graph |
| C. | wait-for graph |
| D. | all of the mentioned |
| Answer» A. read-only graph | |
| 674. |
A deadlock exists in the system if and only if the wait-for graph contains a |
| A. | cycle |
| B. | direction |
| C. | bi-direction |
| D. | rotation |
| Answer» A. cycle | |
| 675. |
rollback requires the system to maintain additional information about the state of all the running transactions. |
| A. | total |
| B. | partial |
| C. | time |
| D. | commit |
| Answer» B. partial | |
| 676. |
If a node is locked in an intention mode, explicit locking is done at a lower level of the tree. This is called |
| A. | intention lock modes |
| B. | explicit lock |
| C. | implicit lock |
| D. | exclusive lock |
| Answer» A. intention lock modes | |
| 677. |
If a node is locked in explicit locking is being done at a lower level of the tree, but with only shared-mode locks. |
| A. | intention lock modes |
| B. | intention-shared-exclusive mode |
| C. | intention-exclusive (ix) mode |
| D. | intention-shared (is) mode |
| Answer» A. intention lock modes | |
| 678. |
If a node is locked in then explicit locking is being done at a lower level, with exclusive-mode or shared-mode locks. |
| A. | intention lock modes |
| B. | intention-shared-exclusive mode |
| C. | intention-exclusive (ix) mode |
| D. | intention-shared (is) mode |
| Answer» C. intention-exclusive (ix) mode | |
| 679. |
If a node is locked in the subtree rooted by that node is locked explicitly in shared mode, and that explicit locking is being done at a lower level with exclusive-mode locks. |
| A. | intention lock modes |
| B. | shared and intention-exclusive (six) mode |
| C. | intention-exclusive (ix) mode |
| D. | intention-shared (is) mode |
| Answer» B. shared and intention-exclusive (six) mode | |
| 680. |
The requires that each transaction Ti executes in two or three different phases in its lifetime, depending on whether it is a read-only or an update transaction. |
| A. | validation protocol |
| B. | validation-based protocol |
| C. | timestamp protocol |
| D. | timestamp-ordering protocol |
| Answer» A. validation protocol | |
| 681. |
denotes the largest timestamp of any transaction that executed write(Q) successfully. |
| A. | w-timestamp(q) |
| B. | r-timestamp(q) |
| C. | rw-timestamp(q) |
| D. | wr-timestamp(q) |
| Answer» A. w-timestamp(q) | |
| 682. |
The most recent version of standard SQL prescribed by the American National Standards Institute is |
| A. | sql 2016 |
| B. | sql 2002 |
| C. | sql – 4 |
| D. | sql2 |
| Answer» A. sql 2016 | |
| 683. |
ANSI-standard SQL allows the use of special operators in conjunction with the WHERE clause. A special operator used to check whether an attribute value is null is |
| A. | between |
| B. | is null |
| C. | like |
| D. | in |
| Answer» B. is null | |
| 684. |
A lock that prevents the use of any tables in the database from one transaction while another transaction is being processed is called a |
| A. | database-level lock |
| B. | table-level lock |
| C. | page-level lock |
| D. | row-level lock |
| Answer» A. database-level lock | |
| 685. |
A condition that occurs when two transactions wait for each other to unlock data is known as a(n) |
| A. | shared lock |
| B. | exclusive lock |
| C. | binary lock |
| D. | deadlock |
| Answer» D. deadlock | |
| 686. |
The file organization which allows us to read records that would satisfy the join condition by using one block read is |
| A. | heap file organization |
| B. | sequential file organization |
| C. | clustering file organization |
| D. | hash files organization |
| Answer» C. clustering file organization | |
| 687. |
The extent of the database resource that is included with each lock is called the level of |
| A. | impact |
| B. | granularity |
| C. | management |
| D. | dbms control |
| Answer» B. granularity | |
| 688. |
DBMS periodically suspends all processing and synchronizes its files and journals through the use of |
| A. | checkpoint facility |
| B. | backup facility |
| C. | recovery manager |
| D. | database change log |
| Answer» A. checkpoint facility | |
| 689. |
Snapshot isolation is used to give |
| A. | transaction a snapshot of the database |
| B. | database a snapshot of the transaction |
| C. | database a snapshot of committed values in the transaction |
| D. | transaction a snapshot of the database and database a snapshot of committed values in the transaction |
| Answer» D. transaction a snapshot of the database and database a snapshot of committed values in the transaction | |
| 690. |
Lost update problem is |
| A. | second update overwrites the first |
| B. | first update overwrites the second |
| C. | the updates are lost due to conflicting problem |
| D. | none of the mentioned |
| Answer» A. second update overwrites the first | |
| 691. |
Each of a pair of transactions has read data that is written by the other, but there is no data written by both transactions, is referred to as |
| A. | read skew |
| B. | update skew |
| C. | write lock |
| D. | none of the mentioned |
| Answer» D. none of the mentioned | |
| 692. |
Which statements are correct regarding indexes? |
| A. | when a table is dropped, the corresponding indexes are automatically dropped |
| B. | for each dml operation performed, the corresponding indexes are automatically updated |
| C. | a non-deferrable primary key or unique key constraint in a table automatically creates a unique index |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| 693. |
A non-correlated subquery can be defined as |
| A. | a set of sequential queries, all of which must always return a single value |
| B. | a set of sequential queries, all of which must return values from the same table |
| C. | a select statement that can be embedded in a clause of another select statement only |
| D. | a set of one or more sequential queries in which generally the result of the inner query is used as the search value in the outer query |
| Answer» D. a set of one or more sequential queries in which generally the result of the inner query is used as the search value in the outer query | |
| 694. |
Which statement is true regarding synonyms? |
| A. | synonyms can be created for tables but not views |
| B. | synonyms are used to reference only those tables that are owned by another user |
| C. | a public synonym and a private synonym can exist with the same name for the same table |
| D. | the drop synonym statement removes the synonym, and the status of the table on which the synonym has been created becomes invalid |
| Answer» C. a public synonym and a private synonym can exist with the same name for the same table | |
| 695. |
The method of access that uses key transformation is called as |
| A. | direct |
| B. | hash |
| C. | random |
| D. | sequential |
| Answer» B. hash | |
| 696. |
Why do we need concurrency control on B+ trees ? |
| A. | to remove the unwanted data |
| B. | to easily add the index elements |
| C. | to maintain accuracy of index |
| D. | all of the mentioned |
| Answer» C. to maintain accuracy of index | |
| 697. |
How many techniques are available to control concurrency on B+ trees? |
| A. | one |
| B. | three |
| C. | four |
| D. | none of the mentioned |
| Answer» D. none of the mentioned | |
| 698. |
In crabbing protocol locking |
| A. | goes down the tree and back up |
| B. | goes up the tree and back down |
| C. | goes down the tree and releases |
| D. | goes up the tree and releases |
| Answer» A. goes down the tree and back up | |
| 699. |
The deadlock can be handled by |
| A. | removing the nodes that are deadlocked |
| B. | restarting the search after releasing the lock |
| C. | restarting the search without releasing the lock |
| D. | resuming the search |
| Answer» B. restarting the search after releasing the lock | |
| 700. |
In crabbing protocol, the lock obtained on the root node is in mode. |
| A. | shared |
| B. | exclusive |
| C. | read only |
| D. | none of the mentioned |
| Answer» A. shared | |
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