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Recent questions tagged decomposition

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2NF DECOMPOSITION
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GO Classes 2024 | IIITH Mock Test 5 | Question: 10
Let $\text{R}_1, \text{R}_2, \ldots, \text{R}_n$ be a decomposition of schema $\text{U}$. Let $u(\text{U)}$ ... \bowtie r_2 \bowtie \cdots \bowtie r_n$u \neq r_1 \bowtie r_2 \bowtie \cdots \bowtie r_n$
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Sel doubt
Relation R (A,B,C,D,E,F)Functional dependency: ABC -->DEF, BC-->EF, EF-->D.Decomposition: R1 (ABCDF), R2 (BCDE). ... preserve functional dependency?Plz explain how to check functional dependency is preserved or not in decomposition.
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Self doubt dbms Normalisation
Is minimal set of functional dependency for a functional dependency set is always unique???
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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 ... R in 3NF? if not, decompose to 3NF.//What does " with A as the only key" mean ?
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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 ... the algorithm.FD's are $M\rightarrow O, NO\rightarrow P, P\rightarrow L, L\rightarrow MN$
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Lossless join
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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 ... .But here the image above,it is comming as loseless join.Can someone please check?
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lossless join
$R(X,Y,Z,W) is\ decomposed\ into \\ R_1(X,Y)\\ R_2(Y,Z)\\ R_3(Y,W).\\The\ FDs\ are\ :\\ X -> Y,\\ Z->Y,\\ Y->W \\ Find\ whether\ the\ decomposition\ is\ lossless\ or\ lossy\ ?$
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NORMALIZTION
Q.Let R (X, Y, Z, W) be a relational schema with the following functional dependencies: X→ Y, Y → ... preserving or not ?I am sure it is lossless join,but couldn't figure how it is dependency preserving.
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2NF decomposition
How is it option D??
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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 __________________________.
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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 ... decomposition.Can anyone explain me this with different analogy or help me visualize it.
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DBMS-Decomposition
Which of the following statement is true while decomposition ? 3NF guaranteed dependency preserving3NF guaranteed lossless propertyBoth of the aboveNone of the above
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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 ... , tell what will be the candidate key after performing join each time and at the end.
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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 BCNF ?How many minimum tables which satisfy 4NF ?
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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 ina. 1NF but not 2NFb. 2NF but not 3NFc. 3NF but not BCNFd. BCNF
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DBMS-Normalisation-Lossless Join Decomposition
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Lossy join decomposition
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Database mgmt system
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"={ DIJ, ACE, FGH, ... ->B, AD->E, B->D, BC->A, E->Ga) D=( ABC, ACDE, ADG)
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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 ... is lossy.Only $I$Only $II$Both $I$ and $II$Neither $I$ nor $II$
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Checking for lossless-join property
The decomposition of relation R with FD set F into R1 and R2 has lossless join property iffR1 $\cap$ R2 $\rightarrow$ R1 $\in$ F$^+$ ... check for lossless join property ?Answers with reference(s) will be much appreciated. Thanks.
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UGC NET CSE | June 2011 | Part 2 | Question: 20
Decomposition help in eliminating some of the problems of bad designRedundancyInconsistenciesAnomaliesAll of the above
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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$R_1 \cap R_2 \twoheadrightarrow (R_1-R_2)$ ... $\text{i and iii}$ happen$\text{ii and iii}$ happen
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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 ... R_2$(R_1 \cap R_2) \rightarrow R_1 \text{ and } R_1 \cap R_2 \rightarrow R_2$
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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--> CB. A-->BC and AB--> CC. A--> BC and A--> BD. A--> B and B--> C
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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--> QM--> RQN--> RR--> STNext consider the following set of ... / have lossless join property?A. Only D1B. Only D2C. Both D1 and D2D. Neither D1 nor D2
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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 $AB, CD$ ... \rightarrow A$A \rightarrow B, B \rightarrow A, C \rightarrow D, D \rightarrow C$
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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
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