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Recent questions tagged data-dependences

2 votes
2 answers
1
Consider a relational schema $S=(U,V,W,X,Y,Z)$ on which the following functional dependencies hold: $(U \rightarrow V, VW \rightarrow X, Y \rightarrow W, X \rightarrow U)$ Which are the candidate keys among following options? $UY, VY$ $UY, VY, XY$ $UYZ, VYZ, VWZ$ $UYZ, VYZ, XYZ$
asked Nov 20, 2020 in Databases jothee 128 views
2 votes
2 answers
2
A functional dependency of the form $x\to y$ is trivial if $y\subseteq x$ $y\subset x$ $x\subseteq y$ $x\subset y\:\text{and}\:y\subset x$
asked Apr 2, 2020 in Databases Lakshman Patel RJIT 644 views
0 votes
2 answers
3
Given the following relation instance: $\begin{array}{ccc} X & Y & Z \\ \hline 1 & 4 & 2 \\ 1 & 5 & 3 \\ 1 & 6 & 3 \\ 3 & 2 & 2 \end{array}$ ... $YZ \rightarrow X \text{ and } X \rightarrow Z$ $XZ \rightarrow Y \text{ and } Y \rightarrow X$
asked Apr 2, 2020 in Databases Lakshman Patel RJIT 148 views
0 votes
1 answer
4
Consider the schema $R=(\text{S T U V})$ and the dependencies $ S \rightarrow T, T \rightarrow U, U \rightarrow V$, and $V \rightarrow S.$ If $R=(R1 \text{ and } R2)$ be a decomposition such that $R1 \cap R2= \phi$ then decomposition is not in $\text{2 NF}$ in $\text{2 NF}$ but not in $\text{3 NF}$ in $\text{3 NF}$ but not in $\text{2 NF}$ in both $\text{2 NF}$ and $\text{3 NF}$
asked Apr 2, 2020 in Databases Lakshman Patel RJIT 208 views
0 votes
0 answers
7
Which statement is false regarding data independence ? Hierarchical data model suffers from data independence Network model suffers from data independence Relational model suffers only from logical data independence Relational model suffers only from physical data independence
asked Mar 27, 2020 in Databases jothee 72 views
0 votes
1 answer
8
The undesirable multivalued dependency in a relation arises if there exist Two one-to-many relationships between attributes of a relation One one-to-one and one one-to many one relationships between attributes within a relation Two one-to-one relationships between attributes of a relation One one-to-many relationship between attributes across relation
asked Aug 4, 2019 in Databases gatecse 45 views
0 votes
2 answers
10
0 votes
3 answers
12
Consider the following functional dependencies in a database: $A \rightarrow B$ $B \rightarrow C$ $D \rightarrow E$ $E \rightarrow D$ $F \rightarrow G$ $F \rightarrow H$ $(E,F) \rightarrow 1$ The relation $(E,D,A,B)$ is $2$ NF $3$ NF BCNF None of the above
asked Dec 7, 2018 in Databases Arjun 759 views
0 votes
1 answer
13
0 votes
2 answers
14
$I_1 : MUL \ \ \ \ \ R_1, R_2, R_3$ // $R_1 \leftarrow R_2 \times R_3$ $I_2 : ADD \ \ \ \ \ R_4, R_4, R_1$ $I_3 : MUL \ \ \ \ \ R_1, R_5, R_6$ $I_4 : SUB \ \ \ \ \ R_4, R_4, R_1$ Sum of RAW, WAR and WAW dependencies is _____.
asked Oct 23, 2018 in CO and Architecture Mk Utkarsh 218 views
2 votes
1 answer
15
Consider the below instructions executed on a 5 stage(IF,ID,EX,MA,WB) RISC pipeline with operand forwarding. I1: ADD R0,R1,R2 (R0=R1+R2) I2: SUB R3,R0,R2 I3:MUL R4,R3,R0 I4:DIV R5,R4,R0 How many RAW dependencies?
asked Oct 23, 2018 in CO and Architecture Mk Utkarsh 878 views
0 votes
1 answer
16
Anti- dependency will not ALWAYS create stall because we can use register renaming to remove stall. Please confirm below statement: Anti-dependency MAY create stall (True/False)
asked Sep 23, 2018 in CO and Architecture Suneel Padala 120 views
1 vote
1 answer
18
J1: R1 = 100 J2: R1 = R2 + R4 J3: R2 = R4 + 25 J4: R4 = R1 + R3 J5: R1 = R1 + 30 Give the no of RAW, WAR and WAW hazards
asked Dec 3, 2017 in CO and Architecture Tuhin Dutta 960 views
4 votes
1 answer
19
R4 <- R1 + R4 R4 <- R2 + R4 R4 <- R3 + R5 Number of WAR and WAW dependencies?
asked Nov 4, 2017 in CO and Architecture Rajesh R 388 views
0 votes
0 answers
20
R(ABCDE) { A,BC,CD} are candidate key of relation R after 1 NF design which one is possible multi valued attributes before 1 NF design ???
asked Oct 27, 2017 in Databases air1ankit 122 views
3 votes
1 answer
21
Number of WAR dependencies possible R1 <- R3 + R2 R3 <- R3 + R5 R3 <- R2 + R3 Is it 2 or 3?
asked Oct 26, 2017 in CO and Architecture Rajesh R 184 views
0 votes
1 answer
22
1- R(ABCD) FD'S ARE {AB->C ,C->D,D->EA ,DE->F,EF->B} 2-R(ABCD) FDS ARE { A->BC, CD->E, B->D,E-A} 3- R(ABCD) {AB-> CD,C->B,D->C} Find the candidate key ??? For above questions and please explain too.
asked Oct 17, 2017 in Databases air1ankit 175 views
1 vote
2 answers
23
Consider the following instructions. I​ 1​ : R​ 1​ = 100 I​ 2​ : R​ 1​ = R​ 2​ + R​ 4 I​ 3​ : R​ 2​ = R​ 4​ + 25 I​ 4​ : R​ 4​ = R​ 1​ + R​ 3 I​ 5​ : R​ 1​ = R​ 1​ + 30 Calculate sum of (WAR, RAW and WAW) dependencies the above instructions. (a) 10 (c) 6 (b) 12 (d) 8
asked Sep 28, 2017 in CO and Architecture sunil sarode 1.6k views
1 vote
0 answers
24
If asked to count the number of RAW dependencies, do we consider only adjacent instructions or both adjacent and non-adjacent? Please explain in detail.
asked Sep 28, 2017 in CO and Architecture Warlock lord 70 views
1 vote
1 answer
25
For relation R=(L, M, N, O, P), the following dependencies hold: M→O, NO→P, P→Land L→MN R is decomposed into R1 = (L, M, N, P) and R2 = (M, O).What is the highest normal form satisfied by the above decomposition? My doubt is For R1 it is in 2NF and R2 it is in BCNF .But ,dependency preserving also violates .So whts the highest normal form ?
asked Jul 25, 2017 in Databases set2018 152 views
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