Recent questions tagged decomposition / GATE Overflow for GATE CSE

0 votes

1 answer

1

2NF DECOMPOSITION

ROMITDUTTA

218 views

ROMITDUTTA asked Jul 5, 2023

1 votes

0 answers

2

Sel doubt
Relation R (A,B,C,D,E,F) Functional dependency: ABC -->DEF, BC-->EF, EF-->D. Decomposition: R1 (ABCDF), R2 (BCDE). Is this decomposition lossy? Is this decomposition preserve functional dependency? Plz explain how to check functional dependency is preserved or not in decomposition.

Relation R (A,B,C,D,E,F)Functional dependency: ABC >DEF, BC >EF, EF >D.Decomposition: R1 (ABCDF), R2 (BCDE). Is this decomposition lossy?Is this decomposition pres...

Raj Kumar 7

1.1k views

Raj Kumar 7 asked Dec 24, 2018

2 votes

2 answers

3

Self doubt dbms Normalisation
Is minimal set of functional dependency for a functional dependency set is always unique???

Is minimal set of functional dependency for a functional dependency set is always unique???

gatecrack

601 views

gatecrack asked Dec 10, 2018

2 votes

2 answers

4

Function Dependency question
Consider a relation R(A,B,C,D,E,F,H) with A as the only key. Assume that the dependencies E->F and C-> DEH hold.on R. 1. Is R in 2NF? If not, decompose to 2NF. 2. is R in 3NF? if not, decompose to 3NF. //What does " with A as the only key" mean ?

Consider a relation R(A,B,C,D,E,F,H) with A as the only key. Assume that the dependencies E->F and C- DEH hold.on R.1. Is R in 2NF? If not, decompose to 2NF.2. is R in 3N...

karthikmenon

1.1k views

karthikmenon asked Jun 23, 2018

1 votes

1 answer

5

Self - Doubt : How to calculate candidate keys in decomposed Relation?
For relation R=(L, M, N, O, P), the following dependencies hold and R is decomposed into R1 = (L, M, N, P) and R2 = (M, O). How to calculate what candidate keys are there for relation R1 and R2. Please tell me the algorithm. FD's are $M\rightarrow O, NO\rightarrow P, P\rightarrow L, L\rightarrow MN$

For relation R=(L, M, N, O, P), the following dependencies hold and R is decomposed into R1 = (L, M, N, P) and R2 = (M, O). How to calculate what candidate keys are there...

Durgesh Singh

774 views

Durgesh Singh asked May 1, 2018

1 votes

1 answer

6

Lossless join

Mk Utkarsh

1.0k views

Mk Utkarsh asked Jan 12, 2018

0 votes

0 answers

7

DBMS Losless join
R is divided into R1 and R2 ,but since there is no common attribute in R1 and R2, so it should form lossy join,as for loseless join the common attribute has to be key in one of the table.But here the image above,it is comming as loseless join.Can someone please check?

R is divided into R1 and R2 ,but since there is no common attribute in R1 and R2, so it should form lossy join,as for loseless join the common attribute has to be key in ...

rahul sharma 5

481 views

rahul sharma 5 asked Dec 12, 2017

1 votes

2 answers

8

lossless join
$R(X,Y,Z,W) is\ decomposed\ into \\ R_1(X,Y)\\ R_2(Y,Z)\\ R_3(Y,W).\\The\ FDs\ are\ :\\ X -> Y,\\ Z->Y,\\ Y->W \\ Find\ whether\ the\ decomposition\ is\ lossless\ or\ lossy\ ?$

$R(X,Y,Z,W) is\ decomposed\ into \\ R_1(X,Y)\\ R_2(Y,Z)\\ R_3(Y,W).\\The\ FDs\ are\ :\\ X - Y,\\ Z->Y,\\ Y->W \\ Find\ whether\ the\ decomposition\ is\ lossless\ or\ ...

Tuhin Dutta

614 views

Tuhin Dutta asked Dec 8, 2017

2 votes

1 answer

9

NORMALIZTION
Q.Let R (X, Y, Z, W) be a relational schema with the following functional dependencies: X→ Y, Y → Z, Z → W and W → Y. The decomposition of R into (X, Y), (Y, Z), (Y, W) it is asked to find whether it is lossless join and dependency preserving or not ? I am sure it is lossless join,but couldn't figure how it is dependency preserving.

Q.Let R (X, Y, Z, W) be a relational schema with the following functional dependencies: X→ Y, Y → Z, Z → W and W → Y.The decomp...

junaid ahmad

2.0k views

junaid ahmad asked Dec 6, 2017

3 votes

2 answers

10

2NF decomposition
How is it option D??

How is it option D??

Parshu gate

3.6k views

Parshu gate asked Nov 19, 2017

1 votes

2 answers

11

virtual gate
Relation R(ABCDEF) with the following set of functional dependencies {AB→CDEF, C→A, D→B, E→F, B→E}. The decomposed relationslations of R into 3NF are __________________________.

Relation R(ABCDEF) with the following set of functional dependencies {AB→CDEF, C→A, D→B, E→F, B→E}.The decomposed relationslations of R into 3NF are ___________...

Manoja Rajalakshmi A

3.2k views

Manoja Rajalakshmi A asked Nov 13, 2017

2 votes

2 answers

12

lossless decomposition
I know the condition for a 2 table to be lossless, but i cannot visualize it. How is 1 table which is decomposed, and if common attribute is key in any one of table, then its lossless decomposition. Can anyone explain me this with different analogy or help me visualize it.

I know the condition for a 2 table to be lossless, but i cannot visualize it.How is 1 table which is decomposed, and if common attribute is key in any one of table, then ...

Aman Bisht 1

713 views

Aman Bisht 1 asked Sep 29, 2017

0 votes

2 answers

13

DBMS-Decomposition
Which of the following statement is true while decomposition ? 3NF guaranteed dependency preserving 3NF guaranteed lossless property Both of the above None of the above

Which of the following statement is true while decomposition ? 3NF guaranteed dependency preserving3NF guaranteed lossless propertyBoth of the aboveNone of the above

rishu_darkshadow

590 views

rishu_darkshadow asked Sep 21, 2017

0 votes

1 answer

14

Testing Lossless join
State true or false:- Symbol " ^ " stands for an intersection AND letters in bold are the candidate key of the respective table. 1) R1(A, B, C) ^ R2(B, C) = {B,C} IS LOSSLESS JOIN. 2) R1(A, B, C) ^ R2(B, D) = {B} IS LOSSY JOIN. 3) R1(A, B ... C), R2(D, E), R3(F, B), R4(D, G, A) Also, tell what will be the candidate key after performing join each time and at the end.

State true or false:-Symbol " ^ " stands for an intersection AND letters in bold are the candidate key of the respective table.1) R1(A, B, C) ^ R2(B, C) = {B,C} IS LOSSL...

Shubhanshu

643 views

Shubhanshu asked May 3, 2017

8 votes

2 answers

15

Higher normal form decomposition
$X$ is an entity set. $E$ and $F$ are multivalued attributes. How many minimum tables which satisfy 1NF ? How many minimum tables which satisfy 2NF ? How many minimum tables which satisfy 3NF ? How many minimum tables which satisfy BCNF ? How many minimum tables which satisfy 4NF ?

$X$ is an entity set. $E$ and $F$ are multivalued attributes.How many minimum tables which satisfy 1NF ?How many minimum tables which satisfy 2NF ?How many minimum tables...

dd

2.5k views

dd asked Feb 1, 2017

3 votes

2 answers

16

DBMS Normalisation
Consider a schema R(A, B, C, D) and functional dependencies {AB → C, C → D, D→ A}. Then the decomposition of R into R1 (CD), R2 (AC) and R3 (BC) is in a. 1NF but not 2NF b. 2NF but not 3NF c. 3NF but not BCNF d. BCNF

Consider a schema R(A, B, C, D) and functional dependencies {AB → C, C → D, D→ A}. Then the decomposition of R into R1 (CD), R2 (AC) and R3 (BC) is ina. 1NF but not...

sanyam53

896 views

sanyam53 asked Jan 11, 2017

3 votes

4 answers

17

DBMS-Normalisation-Lossless Join Decomposition

KISHALAY DAS

1.2k views

KISHALAY DAS asked Dec 21, 2016

2 votes

1 answer

18

Lossy join decomposition

Rakesh K

1.3k views

Rakesh K asked Dec 9, 2016

0 votes

1 answer

19

Database mgmt system
Tell whether the following decomposition of relations lossless and dependency preserving or not. 1. R(ABCDEFGHIJ) and FD sets AB->C, A->DE, B->F, F->GH, D->IJ a) D1"={ DIJ, ACE, FGH, BF, ADC} b) D2={ FGH, DIJ, ADEBF, ABC} 2.R(ABCDEG) and FD sets AB->C, AC->B, AD->E, B->D, BC->A, E->G a) D=( ABC, ACDE, ADG)

Tell whether the following decomposition of relations lossless and dependency preserving or not.1. R(ABCDEFGHIJ) and FD setsAB->C, A->DE, B->F, F->GH, D->IJa) D1"={ DI...

Chetnawadhwa

1.6k views

Chetnawadhwa asked Nov 2, 2016

2 votes

1 answer

20

UGC NET CSE | August 2016 | Part 3 | Question: 10
Consider the table $R$ with attributes $A, B$ and $C$. The functional dependencies that hold on $R$ are : $A \rightarrow B, C \rightarrow AB$. Which of the following statements is/are True ? I. The decomposition of $R$ into $R1(C, A)$ and $R2(A, B)$ is ... $R1(A, B)$ and $R2(B, C)$ is lossy. Only $I$ Only $II$ Both $I$ and $II$ Neither $I$ nor $II$

Consider the table $R$ with attributes $A, B$ and $C$. The functional dependencies that hold on $R$ are : $A \rightarrow B, C \rightarrow AB$. Which of the following stat...

makhdoom ghaya

2.0k views

makhdoom ghaya asked Sep 30, 2016

4 votes

1 answer

21

Checking for lossless-join property
The decomposition of relation R with FD set F into R1 and R2 has lossless join property iff R1 $\cap$ R2 $\rightarrow$ R1 $\in$ F$^+$ OR R1 $\cap$ R2 $\rightarrow$ R2 $\in$ F$^+$ If R is decomposed into more than 2 ... ? Or is that table drawing thing the only way to check for lossless join property ? Answers with reference(s) will be much appreciated. Thanks.

The decomposition of relation R with FD set F into R1 and R2 has lossless join property iffR1 $\cap$ R2 $\rightarrow$ R1 $\in$ F$^+$ ORR1 $\cap$ R2 $\rightarrow$ R2 $\in...

Rounak Agarwal

1.0k views

Rounak Agarwal asked Sep 22, 2016

2 votes

3 answers

22

UGC NET CSE | June 2011 | Part 2 | Question: 20
Decomposition help in eliminating some of the problems of bad design Redundancy Inconsistencies Anomalies All of the above

Decomposition help in eliminating some of the problems of bad designRedundancyInconsistenciesAnomaliesAll of the above

makhdoom ghaya

2.4k views

makhdoom ghaya asked Aug 23, 2016

5 votes

1 answer

23

UGC NET CSE | Junet 2015 | Part 3 | Question: 11
The relation schemas $R_1$ and $R_2$ form a Lossless join decomposition of $R$ if and only if $R_1 \cap R_2 \twoheadrightarrow (R_1-R_2)$ $R_1 \rightarrow R_2$ $R_1 \cap R_2 \twoheadrightarrow (R_2-R_1)$ $R_2 \rightarrow R_1 \cap R_2$ $\text{i and ii}$ happen $\text{i and iv}$ happen $\text{i and iii}$ happen $\text{ii and iii}$ happen

The relation schemas $R_1$ and $R_2$ form a Lossless join decomposition of $R$ if and only if$R_1 \cap R_2 \twoheadrightarrow (R_1-R_2)$$R_1 \rightarrow R_2$$R_1 \cap R_2...

go_editor

4.2k views

go_editor asked Jul 31, 2016

1 votes

2 answers

24

UGC NET CSE | December 2012 | Part 3 | Question: 56
If a relation with a Schema R is decomposed into two relations $R_1$ and $R_2$ such that $(R_1 \cup R_2) = R_1$ then which one of the following is to be satisfied for a lossless joint decomposition ($\rightarrow$ indicates functional ... $(R_1 \cap R_2) \rightarrow R_1 \text{ and } R_1 \cap R_2 \rightarrow R_2$

If a relation with a Schema R is decomposed into two relations $R_1$ and $R_2$ such that $(R_1 \cup R_2) = R_1$ then which one of the following is to be satisfied for a l...

go_editor

3.0k views

go_editor asked Jul 13, 2016

2 votes

4 answers

25

Canonical cover of a set
Consider the following set of functional dependency on the scheme (A, B,C) A-->BC, B-->C, A--> B, AB-->C The canonical cover for this set is: (A) A-->BC and B--> C B. A-->BC and AB--> C C. A--> BC and A--> B D. A--> B and B--> C

Consider the following set of functional dependency on the scheme (A, B,C) A >BC, B >C, A B, AB >C The canonical cover for this set is:(A) A >BC and B CB. A >BC and AB ...

Purple

18.1k views

Purple asked Jan 24, 2016

1 votes

3 answers

26

Which of the above decomposition has/ have lossless join property?
Consider a relation R= {M, N, O,P, Q, R, S, T} with the following set of dependencies: MN--> Q M--> RQ N--> R R--> ST Next consider the following set of decompositions for the relation schema R: D1= {R1, ... decomposition (s) has/ have lossless join property? A. Only D1 B. Only D2 C. Both D1 and D2 D. Neither D1 nor D2

Consider a relation R= {M, N, O,P, Q, R, S, T} with the following set of dependencies:MN QM RQN RR STNext consider the following set of decompositions for the relatio...

Purple

6.5k views

Purple asked Jan 24, 2016

2 votes

2 answers

27

For which of the following set of functional dependencies does the relation R(A,B,C,D) has AB,CD as closed sets

For which of the following set of functions dependencies does the relation $R(A, B, C, D)$ has $AB, CD$ as closed sets?$A \rightarrow B, B \rightarrow A, C \rightarrow D$...

shiva

2.6k views

shiva asked Dec 25, 2015

0 votes

2 answers

28

how to approach this type of question
i know how to find whether the decomposition is lossless or lossy . but in this type of question they are actually not defining how they decompose . they are only giving a set of functional depenencies . how to solve this type of question

i know how to find whether the decomposition is lossless or lossy . but in this type of question they are actually not defining how they decompose . they are only giving ...

Tendua

410 views

Tendua asked Aug 22, 2015

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