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1 vote
3 answers
1
Consider following schedules involving two transactions: $S_{1}: \: r_{1}(X);r_{1}(Y);r_{2}(X);r_{2}(Y);w_{2}(Y);w_{1}(X)$ $S_{2}: \: r_{1}(X);r_{2}(X);r_{2}(Y);w_{2}(Y);r_{1}(Y);w_{1}(X)$ Which of the ... . $S_1$ is conflict serializable and $S_2$ is not conflict serializable $S_1$ is not conflict serializable and $S_2$ is conflict serializable Both $S_1$ and $S_2$ are not conflict serializable
asked Mar 24 in Databases jothee 163 views
1 vote
1 answer
2
Let $pk(R)$ denotes primary key of relation $R$. A many-to-one relationship that exists between two relation $R_1$ and $R_2$ can be expressed as follows: $pk(R_2)\rightarrow pk(R_1)$ $pk(R_1)\rightarrow pk(R_2)$ $pk(R_2)\rightarrow R_1 \cap R_2$ $pk(R_1)\rightarrow R_1 \cap R_2$
asked Mar 24 in Databases jothee 78 views
0 votes
3 answers
3
For database relation $R(A,B,C,D)$ where the domains of $A,B,C$ and $D$ include only atomic values, only the following functional dependencies and those that can be inferred from them are: $A \rightarrow C$ $B \rightarrow D$ The relation $R$ is in First ... well as in second normal form Second normal form but not in third normal form. Both in second normal form as well as in third normal form.
asked Mar 24 in Databases jothee 138 views
0 votes
3 answers
4
Consider the following relation: Works(emp_name, company_name,salary) Here,emp name is primary key. Consider the following SQL query Select emp name From works T where salary > (select avg(salary) from works S where T. company name = S. company name) The above ... salary of all employees all the companies. Find all employees who earn more than the average salary of all employees of their company.
asked Mar 24 in Databases jothee 132 views
0 votes
2 answers
5
If following sequence of keys are inserted in a $B+$ tree with $K(=3)$ pointers: $8,5,1,7,3,12,9,6$ Which of the following shall be correct $B+$ tree?
asked Mar 24 in Databases jothee 82 views
0 votes
2 answers
6
An attribute $A$ of datatype varchar $(20)$ has value 'Ram' and the attribute $B$ of datatype char $(20)$ has value 'Sita' in oracle. The attribute $A$ has ________ memory spaces and $B$ has _______ memory spaces. $20,20$ $3,20$ $3,4$ $20,4$
asked Mar 24 in Databases jothee 93 views
0 votes
2 answers
7
Integrity constraints ensure that changes made to the database by authorized users do not result into loss of data consistency. Which of the following statement(s) is (are) true w.r.t.the examples of integrity constraints? An instructor Id. No. cannot be null, provided Instructor Id No. being primary ... b and c are true. a false, b and c are true. a and b are true; c false. a,b and c are false.
asked Mar 24 in Databases jothee 101 views
0 votes
2 answers
8
Let $M$ and $N$ be two entities in an $E-R$ diagram with simple single value attributes. $R_{1}$ and $R_{2}$ are two relationship between $M$ and $N$, where as $R_{1}$, is one-to-many and $R_{2}$, is many-to-many. The minimum number of tables required to represent $M, N, R_{1}$, and $R_{2}$, in the relational model are ___________. $4$ $6$ $7$ $3$
asked Mar 24 in Databases jothee 162 views
0 votes
3 answers
9
Consider a schema $R(MNPQ)$ and functional dependencies $M\rightarrow N, P\rightarrow Q$. Then the decomposition of $R$ into $R_{1} \left (MN \right )$ and $R_{2} \left (PQ \right )$ is __________. Dependency preserving but not lossless join Dependency preserving and lossless join Lossless join but not dependency preserving Neither dependency preserving nor lossless join.
asked Mar 24 in Databases jothee 56 views
0 votes
1 answer
10
The order of a leaf node in a $B^{+}$ tree is the maximum number of children it can have. Suppose that block size is $1$ kilobytes, the child pointer takes $7$ bytes long and search field value takes $14$ bytes long. The order of the leaf node is _________. $16$ $63$ $64$ $65$
asked Mar 24 in Databases jothee 73 views
0 votes
2 answers
11
__________ refers loosely to the process of semi-automatically analyzing large databases to find useful patterns. Datamining Data warehousing DBMS Data mirroring
asked Mar 24 in Databases jothee 177 views
4 votes
5 answers
12
Consider a relational database containing the following schemas. $\begin{array}{c} \text{Catalogue} \end{array} $ ... (cost) FROM Catalogue WHERE pno = P4' GROUP BY pno) ; The number of rows returned by the above SQL query is $4$ $5$ $0$ $2$
asked Feb 12 in Databases Arjun 1.5k views
6 votes
5 answers
13
Which one of the following is used to represent the supporting many-one relationships of a weak entity set in an entity-relationship diagram? Diamonds with double/bold border Rectangles with double/bold border Ovals with double/bold border Ovals that contain underlined identifiers
asked Feb 12 in Databases Arjun 1.5k views
2 votes
4 answers
14
Consider a relational table $R$ that is in $3NF$, but not in BCNF. Which one of the following statements is TRUE? $R$ has a nontrivial functional dependency $X \rightarrow A$, where $X$ is not a superkey and $A$ is a prime attribute. $R$ has a nontrivial functional dependency ... $X$ is a proper subset of some key A cell in $R$ holds a set instead of an atomic value.
asked Feb 12 in Databases Arjun 1.1k views
3 votes
6 answers
15
Consider a schedule of transactions $T_1$ and $T_2$: $\begin{array}{|c|c|c|c|c|c|c|c|c|c|c|} \hline T_1 & RA & & & RC & & WD & & WB & \text{Commit} & \\ \hline T_2 & & RB & WB & & RD & & WC & & & \text{Commit} \\ \hline \end{array}$ Here, RX stands for Read(X) and WX ...
asked Feb 12 in Databases Arjun 2.7k views
9 votes
3 answers
16
Consider a database implemented using $\text{B+}$ tree for file indexing and installed on a disk drive with block size of $\text{4 KB}$. The size of search key is $\text{12 bytes}$ and the size of tree/disk pointer is $\text{8 bytes}$. ... memory. Consider that each record fits into one disk block. The minimum number of disk accesses required to retrieve any record in the database is _______
asked Feb 12 in Databases Arjun 2.1k views
2 votes
4 answers
17
Properties of $\text{ DELETE'}$ and $\text{ TRUNCATE'}$ commands indicate that After the execution of $\text{ TRUNCATE'}$ operation, $\text{COMMIT}$, and $\text{ROLLBACK}$ statements cannot be performed to retrieve the lost data, while $\text{ DELETE'}$ allow it ... not allow it After the execution of $\text{ DELETE'}$ and $\text{ TRUNCATE'}$ operation no retrieval is possible for the lost data
asked Jan 13 in Databases Satbir 433 views
3 votes
3 answers
18
The SQL query SELECT columns FROM TableA RIGHT OUTER JOIN TableB ON A.columnName = B.columnName WHERE A.columnName IS NULL returns the following: All rows in Table $B$, which meets equality condition above and, none from Table $A$ which meets the condition. All rows ... condition. All rows in Table $B$, which meets the equality condition All rows in Table $A$, which meets the equality condition
asked Jan 13 in Databases Satbir 579 views
4 votes
13 answers
19
If every non-key attribute functionally dependent on the primary key, then the relation will be in First normal form Second normal form Third normal form Fourth Normal form
asked Jan 13 in Databases Satbir 1.4k views
1 vote
1 answer
20
Raymonds tree based algorithm ensures no starvation, but deadlock may occur in rare cases no deadlock, but starvation may occur neither deadlock nor starvation can occur deadlock may occur in cases where the process is already starved
asked Jan 13 in Databases Satbir 187 views
3 votes
2 answers
21
Given two tables $\mathrm{R_1(x,y)}$ and $\mathrm{R_2(y,z)}$ with $50$ and $30$ number of tuples respectively . Find maximum number of tuples in the output of natural join between tables $\mathrm {R_1}$ and $\mathrm{R_2}$ $1)\;30 $ $ 2)\; 20 $ $ 3) \;50 $ $ 4)\; 1500$
asked Dec 20, 2019 in Databases Sanjay Sharma 504 views
0 votes
1 answer
22
The multivalued dependencies (MVDs) can be eliminated using ______ normal form on _____ normal form relations. $1$st, $2$nd $2$nd, $3$rd $3$rd, BCNF $4$th, BCNF
asked Aug 4, 2019 in Others gatecse 80 views
0 votes
1 answer
23
Is basic 2 phase locking always recoverable?
asked Jun 10, 2019 in Databases Hirak 157 views
1 vote
1 answer
24
How to represent referential integrity constraint in ER model? pls explain with diagram
asked Jun 7, 2019 in Databases aditi19 478 views
0 votes
1 answer
25
1 vote
3 answers
26
R(A,B,C) is a relation.Which of the following don't have dependency preserving BCNF decomposition? A->B, B->C A->B,B->C,C->A AB->C,C->A None of these
asked Jun 3, 2019 in Databases ushamya 235 views
0 votes
0 answers
28
A' is set of all possible schedules 'C' is set of all possible schedules that are guaranteed to produce a correct final result 'S' is the set of all serializable schedules 'P' is the set of all schedules possible under 2-phase locking protocol Which is FALSE? $P\subseteq C$ $S\subset P$ $S\subseteq P$ $P\subset C$
asked May 28, 2019 in Databases aditi19 213 views
2 votes
4 answers
29
1 vote
1 answer
30
In a relational algebra ∩ is not a basic operator, to make it basic only relational operator we should have are X, – X, U U, –
asked May 25, 2019 in Databases Hirak 464 views
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