Recent activity in Databases / GATE Overflow for GATE CSE

3 votes

4 answers

1

No. of View equivalent schedules
how many view equivalent schedules are possible for the Sch given below:

how many view equivalent schedules are possible for the Sch given below:

sumit191

2.4k views

sumit191 commented 8 hours ago

1 votes

2 answers

2

GATE CSE 2024 | Set 1 | Question: 10
Let $\mathrm{S}$ be the specification: "Instructors teach courses. Students register for courses. Courses are allocated classrooms. Instructors guide students." Which one of the following $\mathrm{ER}$ diagrams CORRECTLY represents $\mathrm{S}$? $\text{(i)}$ $\text{(ii)}$ $\text{(iii)}$ $\text{(iv)}$

Let $\mathrm{S}$ be the specification: "Instructors teach courses. Students register for courses. Courses are allocated classrooms. Instructors guide students." Which one...

Arjun

2.1k views

Arjun edited 10 hours ago

0 votes

1 answer

3

Minimal Cover
Consider R(A,B,C,D,E,H) be a relational schema with the following functional dependencies: A->BC, CD->E, E->C, D->AEH, ABH->BD, DH->BC Find minimal cover ?

Consider R(A,B,C,D,E,H) be a relational schema with the following functional dependencies:A->BC, CD->E, E->C, D->AEH, ABH->BD, DH->BCFind minimal cover ?

manishankarkanrar

115 views

manishankarkanrar commented 1 day ago

35 votes

5 answers

4

GATE CSE 1990 | Question: 3-ii
Indicate which of the following statements are true: A relational database which is in $3$NF may still have undesirable data redundancy because there may exist: Transitive functional dependencies Non-trivial functional dependencies ... dependencies involving prime attributes only on the left-side. Non-trivial functional dependencies involving only prime attributes.

Indicate which of the following statements are true:A relational database which is in $3$NF may still have undesirable data redundancy because there may exist:Transitive ...

Psy Duck

14.6k views

Psy Duck commented 2 days ago

3 votes

2 answers

5

GATE CSE 2024 | Set 2 | Question: 16
Which of the following file organizations is/are $\text{I/O}$ efficient for the scan operation in $\text{DBMS}$? Sorted Heap Unclustered tree index Unclustered hash index

Which of the following file organizations is/are $\text{I/O}$ efficient for the scan operation in $\text{DBMS}$?SortedHeapUnclustered tree indexUnclustered...

SarthakShastri

2.4k views

SarthakShastri commented 2 days ago

12 votes

2 answers

6

GATE CSE 2022 | Question: 4
In a relational data model, which one of the following statements is $\text{TRUE}?$ A relation with only two attributes is always in $\text{BCNF}.$ If all attributes of a relation are prime attributes, then the relation is in $\text{BCNF}.$ Every relation has at least one non-prime attribute. $\text{BCNF}$ decompositions preserve functional dependencies.

In a relational data model, which one of the following statements is $\text{TRUE}?$A relation with only two attributes is always in $\text{BCNF}.$If all attributes of a r...

SarthakShastri

10.1k views

SarthakShastri commented 2 days ago

0 votes

0 answers

7

Relational Database
Give an appropriate tree-structure diagram for the following relational database: Employee (person_name, street, city) Works (person_name, company_name, salary) Company (company_name, city) Manages (person_name, manager_name)

Give an appropriate tree-structure diagram for the following relational database:Employee (person_name, street, city)Works (person_name, company_name, salary)Company (com...

Shubham Sharma 2

47 views

Shubham Sharma 2 edited 5 days ago

0 votes

1 answer

8

Number of Super Keys
R(A1, A2,A3,A4....AN). How many super keys possible in relation? If (A1 is candidate key, A2 is candidate key, A3 is candidate key)

R(A1, A2,A3,A4....AN). How many super keys possible in relation? If (A1 is candidate key, A2 is candidate key, A3 is candidate key)

ssm

65 views

ssm answer selected 6 days ago

0 votes

0 answers

9

RBR Normalisation example problem
In on of the examples shown by RBR sir, under Normalization I think he did this problem incorrectly, Given relation R(ABC) and fd: AB->C and C->A, convert it into 2NF For this question, the answer according to RBR sir was that the ... "BC", therefore we need to split the tables into AC and ABC is what my solution. Kindly correct me if I am wrong

In on of the examples shown by RBR sir, under Normalization I think he did this problem incorrectly, Given relation R(ABC) and fd: AB->C and C->A, convert it into 2NFFor ...

nareshit

43 views

nareshit asked Apr 15

1 votes

1 answer

10

GATE CSE 2024 | Set 1 | Question: 36
Consider the following read-write schedule $\text{S}$ over three transactions $T_{1}, T_{2}$, and $T_{3}$ ... to $\text{S}$? $T_{1} T_{2} T_{3}$ $T_{1} T_{3} T_{2}$ $T_{3} T_{2} T_{1}$ $T_{3} T_{1} T_{2}$

Consider the following read-write schedule $\text{S}$ over three transactions $T_{1}, T_{2}$, and $T_{3}$, where the subscripts in the schedule indicate trans...

mithikawalkar

2.3k views

mithikawalkar commented Apr 14

1 votes

1 answer

11

normalisation
Suppose you are given a relation R with four attributes ABCD. For each of the following sets of FDs, assuming those are the only dependencies that hold for R, do the following: If R is not in BCNF, decompose it into a set of BCNF relations that preserve the dependencies. AB → C, AB → D, C → A, D → B

Suppose you are given a relation R with four attributes ABCD. Foreach of the following sets of FDs, assuming those are the only dependencies that holdfor R, do the follow...

Ankit Yaduwanshi

2.8k views

Ankit Yaduwanshi commented Apr 12

43 votes

6 answers

12

GATE IT 2004 | Question: 77
Consider the following schedule $S$ of transactions $T1$ and $T2:$ ... only as $T2, T1$ $S$ is serializable both as $T1, T2$ and $T2, T1$ $S$ is not serializable either as $T1,T2$ or as $T2,T1$

Consider the following schedule $S$ of transactions $T1$ and $T2:$$${\begin{array}{l|l}\textbf{T1}& \textbf{T2} \\\hline\text{Read(A)} \\\text{A = A – 10}\\& \text...

Lokesh456

12.4k views

Lokesh456 commented Apr 12

18 votes

3 answers

13

GATE CSE 1994 | Question: 13
Consider the following relational schema: COURSES (cno, cname) STUDENTS (rollno, sname, age, year) REGISTERED_FOR (cno, rollno) The underlined attributes indicate the primary keys for the relations. The year' attribute for the STUDENTS relation indicates the year in ... for cno $322.$ Write a SQL query to print the age and year of the youngest student in each year.

Consider the following relational schema:COURSES (cno, cname)STUDENTS (rollno, sname, age, year)REGISTERED_FOR (cno, rollno)The underlined attributes indicate the primary...

Arghya Jana

6.4k views

Arghya Jana commented Apr 12

0 votes

3 answers

14

is conservative 2PL is recoverable
is conservative 2PL is recoverable schedule ?

is conservative 2PL is recoverable schedule ?

Lokesh456

3.7k views

Lokesh456 commented Apr 10

0 votes

0 answers

15

If P and Q are predicates and P is the relational algebra expression, then which of the following equivalence are valid ? (1) σP(σQ(e)) = σQ(σP(e)). (2) σP(σQ(e)) = σP ∪ Q(e) (3) σP(σP(e)) = σP V Q (4) All of these

SandeepKumar147

58 views

SandeepKumar147 asked Apr 8

23 votes

3 answers

16

GATE CSE 2020 | Question: 13
Consider a relational database containing the following schemas. ... WHERE pno = P4' GROUP BY pno) ; The number of rows returned by the above SQL query is $4$ $5$ $0$ $2$

Consider a relational database containing the following schemas.$$\overset{\text{Catalogue}} {\begin{array}{|c|c|c|} \hline \underline{\text{sno}} & \underline{\text{pno}...

varun_30

13.7k views

varun_30 commented Apr 8

0 votes

0 answers

17

#dbms

L.E.O

91 views

L.E.O commented Apr 8

1 votes

1 answer

18

GATE CSE 2024 | Set 2 | Question: 46
A functional dependency $F: X \rightarrow Y$ is termed as a useful functional dependency if and only if it satisfies all the following three conditions: $\text{X}$ is not the empty set. $\text{Y}$ is not the empty set. Intersection ... set. For a relation $\text{R}$ with $4$ attributes, the total number of possible useful functional dependencies is __________.

A functional dependency $F: X \rightarrow Y$ is termed as a useful functional dependency if and only if it satisfies all the following three conditions:$\text{X}$ is not ...

Yashthakkar

1.8k views

Yashthakkar commented Apr 7

2 votes

1 answer

19

GATE CSE 2024 | Set 2 | Question: 35
The relation schema, Person (pid, city), describes the city of residence for every person uniquely identified by pid. The following relational algebra operators are available: selection, projection, cross product, and rename. To find the list of cities ... above operators, the minimum number of cross product operations that must be used is $1$ $2$ $3$ $4$

The relation schema, Person (pid, city), describes the city of residence for every person uniquely identified by pid. The following relational algebra oper...

noelalexdnn

2.3k views

noelalexdnn commented Apr 7

0 votes

1 answer

20

Relation R(A1, A2, A3 ..... An) n attributes. On this relation m simple candidate key (m ≤ n). How many super keys possible in this relation? A. 2m – 1 B. (2n – 1) ⋅ 2n-m C. 2n – 1 D. (2m – 1) 2n-m

꧁༒☬ĿọŗԀ 🆂🅷🅸🆅🅰☬༒꧂

91 views

꧁༒☬ĿọŗԀ 🆂🅷🅸🆅🅰☬༒꧂ answered Apr 6

5 votes

4 answers

21

UGC NET CSE | June 2016 | Part 3 | Question: 11
Consider the following ORACLE relations: R(A, B, C)={<1, 2, 3>, <1, 2, 0>, <1, 3, 1>, <6, 2, 3>, <1, 4, 2>, <3, 1, 4>} S(B, C, D)={<2, 3, 7>, <1, 4, 5>, <1, 2, 3>, <2, 3, ... of tuples returned by SQ$_1$ and If N is the number of tuples returned by SQ$_2$ then M=4, N=2 M=5, N=3 M=2, N=2 M=3, N=3

Consider the following ORACLE relations:R(A, B, C)={<1, 2, 3>, <1, 2, 0>, <1, 3, 1>, <6, 2, 3>, <1, 4, 2>, <3, 1, 4>}S(B, C, D)={<2, 3, 7>, <1, 4, 5>, <1, 2, 3>, <2, 3, 4...

Bishes

5.5k views

Bishes commented Apr 6

0 votes

0 answers

22

Can a candidate key for a composite attribute be called a composite key?
Let's take an example of student entity type Name Class Section Address (Line1, Line2, City, State, Country, PinCode) Since composite attribute holds multiple atomic attributes, such that the group is treated as ... (ignoring the semantics) the combinations like {Class, Section} {Class, Address} {Name, Class, Section}

Let's take an example of student entity typeNameClassSectionAddress (Line1, Line2, City, State, Country, PinCode)Since composite attribute holds multiple atomic attribute...

tbhaxor

59 views

tbhaxor asked Apr 4

37 votes

5 answers

23

GATE CSE 2018 | Question: 42
Consider the following four relational schemas. For each schema , all non-trivial functional dependencies are listed, The bolded attributes are the respective primary keys. $\text{Schema I:}$ Registration(rollno, courses) Field courses' is a set-valued attribute containing the ... $\text{Schema I}$ $\text{Schema II}$ $\text{Schema III}$ $\text{Schema IV}$

Consider the following four relational schemas. For each schema , all non-trivial functional dependencies are listed, The bolded attributes are the respective primary key...

SarthakShastri

12.0k views

SarthakShastri answered Apr 4

2 votes

2 answers

24

Conflict serializable and 2pl schedule
Can someone write one example of a schedule which is conflict serializable but is not allowed by 2pl protocol. I have read that 2pl-> css, but css-> 2pl is not necessary?

Can someone write one example of a schedule which is conflict serializable but is not allowed by 2pl protocol. I have read that 2pl- css, but css- 2pl is not necessary?

gerteck

4.4k views

gerteck commented Apr 4

0 votes

1 answer

25

S: r3(x) r3(y) w3(x) W2(x) r1(x) w2(y) w3(y) w1(y) How many serial schedules are not view equal to schedule S?

saisri

147 views

saisri answer selected Apr 2

1 votes

2 answers

26

ISI2017-PCB-CS-3-a
Let $R(A,B,C)$ be a relation with primary key $(A)$ and $S(A, D, E)$ a relation with primary key $(A, D)$. Each of the relations has $n$ tuples. If the number of tuples in $R \: \text{ natural join } S$ is $m$, then determine the number of tuples in $R$ $\text{ natural left outer join } S$.

Let $R(A,B,C)$ be a relation with primary key $(A)$ and $S(A, D, E)$ a relation with primary key $(A, D)$. Each of the relations has $n$ tuples. If the number of tuples i...

Abhay123

501 views

Abhay123 answered Mar 31

0 votes

1 answer

27

ISI2020-PCB-CS: 5
In a conference, the relation, $\textsf{registered (participant, topic)}$ stores the names of participants and the topics registered by them. The primary key for this relation is $\textsf{(participant, topic)}.$ ... . Which strategy is faster for $x=3000?$ Justify your answer. Which strategy has less disk access time? Justify your answer.

In a conference, the relation, $\textsf{registered (participant, topic)}$ stores the names of participants and the topics registered by them. The primary key for this rel...

Abhay123

150 views

Abhay123 answered Mar 31

1 votes

1 answer

28

ISI 2021 | PCB CS | Question: 9
In relational algebra, for any pair of relations $R_{1}$ and $R_{2}$, the standard division operation is denoted by $\div$ ...

In relational algebra, for any pair of relations $R_{1}$ and $R_{2}$, the standard division operation is denoted by $\div$ and defined as follows: $$ R_{1} \div R_{2}=\pi...

Abhay123

269 views

Abhay123 answered Mar 31

51 votes

5 answers

29

GATE CSE 2002 | Question: 16
For relation R=(L, M, N, O, P), the following dependencies hold: $ M \rightarrow O,$ $NO \rightarrow P,$ $P \rightarrow L$ and $L \rightarrow MN$ R is decomposed into R1 = (L, M, N, P) and R2 = (M, ... above decomposition dependency-preserving? If not, list all the dependencies that are not preserved. What is the highest normal form satisfied by the above decomposition?

For relation R=(L, M, N, O, P), the following dependencies hold:$ M \rightarrow O,$ $NO \rightarrow P,$ $P \rightarrow L$ and $L \rightarrow MN$R is decomposed into R1 = ...

shikhar500

16.7k views

shikhar500 commented Mar 30

30 votes

2 answers

30

GATE CSE 2009 | Question: 43
Consider two transactions $T_1$ and $T_2$, and four schedules $S_1, S_2, S_3, S_4$, of $T_1$ and $T_2$ as given below: $T_1: R_1[x]W_1[x]W_1[y]$ $T_2: R_2[x]R_2[y]W_2[y]$ $S_1: R_1[x]R_2[x]R_2[y] W_1[x] W_1[y] W_2[y]$ ... $S_1 \text{ and } S_2$ $S_2 \text{ and } S_3$ $S_3$ only $S_4$ only

Consider two transactions $T_1$ and $T_2$, and four schedules $S_1, S_2, S_3, S_4$, of $T_1$ and $T_2$ as given below:$T_1: R_1[x]W_1[x]W_1[y]$$T_2: R_2[x]R_2[y]W_2[y...

SUTAMA

6.7k views

SUTAMA commented Mar 30

tags	tag:apple
author	user:martin
title	title:apple
content	content:apple
exclude	-tag:apple
force match	+apple
views	views:100
score	score:10
answers	answers:2
is accepted	isaccepted:true
is closed	isclosed:true