Recent questions and answers in Databases / GATE Overflow for GATE CSE

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2 answers

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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 ...

ashwinsuthar1

2.0k views

ashwinsuthar1 answered 2 days ago

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2

View serializable
S2: R1(x);r2(z);r3(x);r1(z);r2(y);r3(y);w1(x);w2(z);w3(y);w2(y) Please help

S2: R1(x);r2(z);r3(x);r1(z);r2(y);r3(y);w1(x);w2(z);w3(y);w2(y)Please help

Cjsmwlq

42 views

Cjsmwlq asked 4 days ago

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0 answers

3

B- tree in DBMS

SandeepKumar147

68 views

SandeepKumar147 asked Apr 25

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4

B tree dbms

SandeepKumar147

28 views

SandeepKumar147 asked Apr 25

0 votes

1 answer

5

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

180 views

manishankarkanrar answered Apr 18

0 votes

1 answer

6

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)

manishankarkanrar

113 views

manishankarkanrar answered Apr 18

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...

peter09

81 views

peter09 asked Apr 16

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0 answers

8

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

59 views

nareshit asked Apr 15

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0 answers

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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

79 views

SandeepKumar147 asked Apr 8

0 votes

1 answer

10

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 🆂🅷🅸🆅🅰☬༒꧂

116 views

꧁༒☬ĿọŗԀ 🆂🅷🅸🆅🅰☬༒꧂ answered Apr 6

0 votes

0 answers

11

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

78 views

tbhaxor asked Apr 4

37 votes

5 answers

12

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

12.1k views

SarthakShastri answered Apr 4

1 votes

2 answers

13

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

515 views

Abhay123 answered Mar 31

0 votes

1 answer

14

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

182 views

Abhay123 answered Mar 31

1 votes

1 answer

15

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

293 views

Abhay123 answered Mar 31

0 votes

1 answer

16

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?

L.E.O

178 views

L.E.O answered Mar 29

0 votes

1 answer

17

Explain why BCNF is said to be improved 3NF.

prasantkr.singh

127 views

prasantkr.singh answered Mar 17

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18

File organisation and indexing (DBMS)

Suryadip

116 views

Suryadip asked Mar 9

3 votes

2 answers

19

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...

sanjeet24

2.5k views

sanjeet24 answered Mar 5

0 votes

0 answers

20

#TOC

Çșȇ ʛấẗẻ

62 views

Çșȇ ʛấẗẻ asked Feb 24

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21

#dbms

Çșȇ ʛấẗẻ

100 views

Çșȇ ʛấẗẻ asked Feb 24

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22

NPTEL DBMS (Introduction to Database systems)course Assignment 10: Topic Database Indexing
Use the following information to answer Questions 7 and 8. A sorted file has the following details: Number of records = 13,10,720; record length = 200 bytes; size of the primary key field = 13 bytes; size of ... of blocks in the first level index file is: a)131072 b)1311 c)1310 d)1286 Accepted Answers: 1286

Use the following information to answer Questions 7 and 8.A sorted file has the following details: Number of records = 13,10,720; record length = 200 bytes;size of the pr...

RishabhSahu325

163 views

RishabhSahu325 asked Feb 22

1 votes

3 answers

23

GATE CSE 2024 | Set 1 | Question: 34
The symbol $\rightarrow$ indicates functional dependency in the context of a relational database. Which of the following options is/are TRUE? $(X, Y) \rightarrow(Z, W)$ implies $X \rightarrow(Z, W)$ $(X, Y) \rightarrow(Z, W)$ ... $(X, W) \rightarrow Z$ $(X \rightarrow Y$ and $Y \rightarrow Z)$ implies $X \rightarrow Z$

The symbol $\rightarrow$ indicates functional dependency in the context of a relational database. Which of the following options is/are TRUE?$(X, Y) \rightarrow(Z, W)$...

GauravRajpurohit

2.3k views

GauravRajpurohit answered Feb 18

0 votes

1 answer

24

GATE DS&AI 2024 | Question: 45
An OTT company is maintaining a large disk-based relational database of different movies with the following schema: \[ \begin{array}{l} \text { Movie (ID, CustomerRating) } \\ \text { Genre (ID, Name) } \\ \text { Movie_Genre ... attributes. Hash index on Movie.CustomerRating and $\mathrm{B}^{+}$tree on the remaining attributes. Hash index on all the attributes.

An OTT company is maintaining a large disk-based relational database of different movies with the following schema:\[\begin{array}{l}\text { Movie (ID, ...

liontig37

857 views

liontig37 answered Feb 17

0 votes

2 answers

25

GATE DS&AI 2024 | Question: 21
Consider the following two tables named Raider and Team in a relational database maintained by a Kabaddi league. The attribute ID in table Team references the primary key of the Raider table, ID. Raider ID Name Raids RaidPoints $1$ Arjun $200$ $250$ $2$ ... Jaipur" AND RaidPoints > 200; The number of rows returned by this query is $\_\_\_\_\_\_\_\_$.

Consider the following two tables named Raider and Team in a relational database maintained by a Kabaddi league. The attribute ID in table Team references the primary key...

Hira Thakur

942 views

Hira Thakur answered Feb 17

0 votes

1 answer

26

GATE DS&AI 2024 | Question: 36
Given the relational schema $R=(U, V, W, X, Y, Z)$ and the set of functional dependencies: \[ \{U \rightarrow V, U \rightarrow W, W X \rightarrow Y, W X \rightarrow Z, V \rightarrow X\} \] Which of the following functional dependencies can be derived from the above set? $V W \rightarrow Y Z$ $W X \rightarrow Y Z$ $V W \rightarrow U$ $V W \rightarrow Y$

Given the relational schema $R=(U, V, W, X, Y, Z)$ and the set of functional dependencies:\[\{U \rightarrow V, U \rightarrow W, W X \rightarrow Y, W X \...

Hira Thakur

923 views

Hira Thakur answered Feb 17

2 votes

3 answers

27

GATE CSE 2024 | Set 1 | Question: 11
In a $\mathrm{B}+$ tree, the requirement of at least half-full $(50 \%)$ node occupancy is relaxed for which one of the following cases? Only the root node All leaf nodes All internal nodes Only the leftmost leaf node

In a $\mathrm{B}+$ tree, the requirement of at least half-full $(50 \%)$ node occupancy is relaxed for which one of the following cases?Only the root nodeAll leaf nodesAl...

KASHIF_RAHMAN

2.4k views

KASHIF_RAHMAN answered Feb 17

1 votes

2 answers

28

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...

KASHIF_RAHMAN

2.2k views

KASHIF_RAHMAN answered Feb 17

0 votes

1 answer

29

GATE DS&AI 2024 | Question: 16
Consider a database that includes the following relations: Defender(name, rating, side, goals) Forward(name, rating, assists, goals) Team(name, club, price) Which ONE of the following relational algebra expressions checks that every name occurring in Team appears in ... $\left.)\right) \backslash \Pi_{\text {name }}($ Team $)=\phi$

Consider a database that includes the following relations:Defender(name, rating, side, goals)Forward(name, rating, assists, goals)Team(name, club, price)Wh...

Rahiman159

941 views

Rahiman159 answered Feb 17

3 votes

2 answers

30

GATE CSE 2024 | Set 1 | Question: 12
Which of the following statements about a relation $\mathbf{R}$ in first normal form $\text{(1NF)}$ is/are TRUE? $\mathbf{R}$ can have a multi-attribute key $\mathbf{R}$ cannot have a foreign key $\mathbf{R}$ cannot have a composite attribute $\mathbf{R}$ cannot have more than one candidate key

Which of the following statements about a relation $\mathbf{R}$ in first normal form $\text{(1NF)}$ is/are TRUE?$\mathbf{R}$ can have a multi-attribute key$\mathbf{R}$ ca...

iarpitmishra

3.8k views

iarpitmishra answered Feb 17

1 votes

1 answer

31

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...

Hira Thakur

2.5k views

Hira Thakur answered Feb 16

2 votes

1 answer

32

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...

Deepak Poonia

2.4k views

Deepak Poonia answered Feb 16

1 votes

1 answer

33

GATE CSE 2024 | Set 2 | Question: 17
Which of the following statements about the Two Phase Locking ($2 \mathrm{PL}$) protocol is/are TRUE? $2 \mathrm{PL}$ permits only serializable schedules With $2 \mathrm{PL}$, a transaction always locks the data item being read or ... , no more locks on any data item can be obtained inside that transaction A deadlock is possible with $2 \mathrm{PL}$

Which of the following statements about the Two Phase Locking ($2 \mathrm{PL}$) protocol is/are TRUE?$2 \mathrm{PL}$ permits only serializable schedulesWith $...

supreetshukla

2.1k views

supreetshukla answered Feb 16

1 votes

2 answers

34

GATE CSE 2024 | Set 2 | Question: 9
Once the $\text{DBMS}$ informs the user that a transaction has been successfully completed, its effect should persist even if the system crashes before all its changes are reflected on disk. This property is called durability atomicity consistency isolation

Once the $\text{DBMS}$ informs the user that a transaction has been successfully completed, its effect should persist even if the system crashes before all...

Deepak Poonia

2.3k views

Deepak Poonia answered Feb 16

1 votes

1 answer

35

GATE CSE 2024 | Set 1 | Question: 25
Consider the following two relations, $R(A, B)$ and $S(A, C)$: $R$ $A$ $B$ $10$ $20$ $20$ $30$ $30$ $40$ $30$ $50$ $50$ $95$ $S$ $A$ $C$ $10$ $90$ $30$ $45$ $40$ $80$ The total number of tuples obtained by evaluating the following expression $\sigma_{B<C}\left(R \bowtie_{R . A=S . A} S\right)$ is ___________.

Consider the following two relations, $R(A, B)$ and $S(A, C)$:$R$$A$$B$$10$$20$$20$$30$$30$$40$$30$$50$$50$$95$$S$$A$$C$$10$$90$$30$$45$$40$$80$The total number of tuples...

Hira Thakur

1.9k views

Hira Thakur answered Feb 16

1 votes

1 answer

36

GATE CSE 2024 | Set 2 | Question: 10
In the context of owner and weak entity sets in the $\text{ER}$ (Entity-Relationship) data model, which one of the following statements is TRUE? The weak entity set MUST have total participation in the identifying ... in the identifying relationship Neither weak entity set nor owner entity set MUST have total participation in the identifying relationship

In the context of owner and weak entity sets in the $\text{ER}$ (Entity-Relationship) data model, which one of the following statements is TRUE?The weak entity set MUST h...

supreetshukla

2.0k views

supreetshukla answered Feb 16

6 votes

3 answers

37

GO Classes Test Series 2024 | Mock GATE | Test 14 | Question: 14
A B-Tree of order $m$ is an $m$-way search tree. What is the minimum number of keys that can be stored on the leaf level of a B-Tree of order 20 with 3 levels? (Note: the root of a tree counts as its first level)

A B-Tree of order $m$ is an $m$-way search tree. What is the minimum number of keys that can be stored on the leaf level of a B-Tree of order 20 with 3 levels? (Note: th...

Praveenjha802

709 views

Praveenjha802 answered Feb 7

0 votes

1 answer

38

Memory Based GATE DA 2024 | Question: 16
Consider a relation R: \[ \begin{aligned} & R(U, V, W, X, Y, Z) \\ & F=\left\{ \begin{array}{l} U \rightarrow V \\ U \rightarrow W \\ WX \rightarrow Y \\ WX \rightarrow Z \\ V \rightarrow X \end ... be deduced. Which of the following options is correct? $VW \rightarrow U$ $VW \rightarrow Y$ $VW \rightarrow YZ$ $WX \rightarrow YZ$

Consider a relation R:\[\begin{aligned}& R(U, V, W, X, Y, Z) \\& F=\left\{\begin{array}{l} U \rightarrow V \\ U \rightarrow W \\ WX \rightarrow Y \\�...

Lakshmi Narayana404

236 views

Lakshmi Narayana404 answered Feb 6

4 votes

1 answer

39

GO Classes Test Series 2024 | Mock GATE | Test 14 | Question: 13
Division operator in relational algebra is appropriate to handle which of the following query types? employees work on at most one of the critical projects employees work on any one of the critical projects employees work on at least one of the critical projects employees work on all the critical projects

Division operator in relational algebra is appropriate to handle which of the following query types?employees work on at most one of the critical projectsemployees work o...

GO Classes

400 views

GO Classes answered Feb 5

9 votes

1 answer

40

GO Classes Test Series 2024 | Mock GATE | Test 14 | Question: 41
Consider the following lock requests in the Table below. And note that: $\mathrm{S}(\cdot)$ and $\mathrm{X}(\cdot)$ stand for 'shared lock' and 'exclusive lock', respectively. $T_1, T_2, T_3, T_4$, and $T_5$ represent five ... dead('-'). Select all that are correct. At t3: a At t6: b At t7: a At t8: -

Consider the following lock requests in the Table below. And note that:$\mathrm{S}(\cdot)$ and $\mathrm{X}(\cdot)$ stand for 'shared lock' and 'exclusive lock', respectiv...

GO Classes

787 views

GO Classes answered Feb 5

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