Recent questions and answers in Databases

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Gatebook Test series: Dbms (Indexing/B/B+ Tree)
Consider the following statements S1 : allows rapid random access as well as rapid sequential access. S2 : When a node is split during insertion, the middle key is promoted to the parent as well as retained in right half-node. S3: When a key is deleted from ... For $S_{3}$ they have given it as false. How? It should be true acc. to me & $S_{4}$)

asked 1 hour ago in Databases by Kushagra गुप्ता (83 points) | 5 views

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Self-Doubt on Partial dependency
1NF 2NF 3NF BCNF when a non-prime attribute depends on the prime attribute then it becomes a partial dependency My Doubt is: when a non-prime attribute depends on the Primary key itself or any of the candidate key(but not on key attribute), then, in that case, what happens? Will it be partial dependency or not?

asked 21 hours ago in Databases by Rudr Pawan (577 points) | 26 views

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NPTEL Assignment: Dbms
Given the memory can hold 5 blocks at a time. Also, it is known that size of data is 64MB and size of each block is 1 MB. How many merge passes are required to sort the whole data in external merge-sort, after the initial sort pass, when sorted ... anyone having any idea how to solve, do tell. Even I can provide you the answer for some help that I am unable to understand)

answered 21 hours ago in Databases by chandrikabhuyan8 (88 points) | 22 views

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Gatebook Test series: Dbms (Indexing)
Consider the database EMPLOYEE and file parameters given below EMPLOYEE field and sizes 4 B Suppose that the file is not ordered by the key field and we want to construct a access structure (index) on . Let P be the branch-node order, and be the leaf-node order, ... First one or second one? (P-1)(Key+$R_{p}$)+6B$\leqslant$512B P(Key+$R_{p}$)+6B$\leqslant$512B

asked 21 hours ago in Databases by Kushagra गुप्ता (83 points) | 8 views

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NPTEL Assignment: Dbms (Indexing)
Calculate branching factor in case for B- tree index structure, given: page size: 16 kB, key-size: 16 bytes, pointer size = 8 bytes ? 255 256 510 511 (Note: The answer I am getting is 512 but the given answer is 511. Is my answer correct & if not please tell the approach.)

asked 23 hours ago in Databases by Kushagra गुप्ता (83 points) | 9 views

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NPTEL Assignment : DBMS
BCNF 4NF PJNF DKNF

asked 2 days ago in Databases by Kushagra गुप्ता (83 points) | 13 views

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DBMS ACE Test Series 30 Q26
What is the best strategy to approach these kind of questions? I am facing difficulties in solving indexing numericals. Any help would be highly appreciated. Thank you.

answered 2 days ago in Databases by Mk Utkarsh (153 points) | 25 views

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MADE EASY TEST 2020

answered 4 days ago in Databases by Priyansh Singh (41 points) | 24 views

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N ary Relation Table
“For an n-ary relationship set with an arrow on one of its edges, the primary keys of the entitysets not on the “arrow” side of the relationship set serve as the primary key for the schema.” Can anyone please explain the following statement with some example.

asked 4 days ago in Databases by Shivateja MST (35 points) | 8 views

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self doubt- database
let's consider 3 entity sets $E_1, E_2, E_3$. There is one to one total relation between $E_1$ and $E_2$. There is also a one to one partial relation between $E_2$ and $E_3$. what is the minimum number of tables that are required to convert this E-R diagram into relation schemas. ... $D, E$. $E_3$ have attributes $F, G$ then why can't we use table schema like $(A,B,C,D,E,F,G)$.

answered 4 days ago in Databases by Satbir (2.5k points) | 9 views

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Self_Doubt DBMS-decomposition
Consider we have a relation R(ABCD) and FDs AB→C,C→AD. And we decomposed the relation as R1 (ABC) and R2 (CAD) so FD AB→C goes to R1 & C→AD goes to R2. My doubt is do we have FD C→A in relation R1 (after decomposition). C→AD is already in ... we check for highest normal form? For example, if we consider C→A in R1, then R1 is not in BCNF. Otherwise R1 is in BCNF.

asked 4 days ago in Databases by Amal (23 points) | 8 views

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Database management system 3e by Raghu Ramakrishnan

asked 5 days ago in Databases by Vimal Patel (221 points) | 32 views

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Raghu Ramakrishnan-3e-Chapter 17-Exercise 17.2
Serializable: ? CSS: ? VSS: ? Recoverable: ? Avoid cascading abort:? Strict: ? S1 YES YES YES YES YES NO S2 NO NO NO NO NO NO S3 YES YES YES NO NO NO S1: T1:R(X), T2:W(X), T1:W(X), T2:Abort, T1:Commit S2: ... T2:Commit, T1:Abort Please someone explain me the reason why we are getting such an answer & specially I am facing difficulty due to abort !

asked Oct 15 in Databases by Kushagra गुप्ता (83 points) | 21 views

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testbook test
We consider the cardinality of an entity at opposite end ,then why it is wrong?

answered Oct 15 in Databases by Rudr Pawan (577 points) | 19 views

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MADE EASY FULL LENGTH: DBMS
How can the ans be C? See that here we are applying the inner condition on Adoption table which have different entries, on the other hand the outer query which checks for NOT exists works on ANIMAL table which has different attributes.. So ans should be d right?

answered Oct 14 in Databases by Rudr Pawan (577 points) | 15 views

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Self doubt-View serializability
Whether they are view serialiazable or not? S1: $R_{2}(A)R_{2}(B)W_{2}(A)W_{1}(A)R_{3}(A)W_{1}(B)W_{2}(B)W_{3}(B)$ S2: $R_{1}(A)R_{2}(A)R_{3}(A)R_{4}(A)W_{1}(B)W_{2}(B)W_{3}(B)W_{4}(B)$ ... (Note: Do not take the help of Conflict serializability.)

asked Oct 14 in Databases by Kushagra गुप्ता (83 points) | 31 views

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Self-Doubt DBMS Serializability
If the question is like: Given schedule is serializable or not? then what should be the approach to answer this question means 1). whether we should check for conflict serializability and if conflict serializable then declare the schedule as serializable ... be easier and time-saving. PS: One of the video solutions from MADE EASY test series originated this doubt.

answered Oct 11 in Databases by HeartBleed (52 points) | 22 views

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Kenneth Rosen-7th edition-Chapter 9:Relations-Exercise:9.6

asked Oct 10 in Databases by Kushagra गुप्ता (83 points) | 21 views

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Diffrerence between Functional Dependency and Fully Functionally Dependency on primary Key

asked Oct 10 in Databases by HeartBleed (52 points) | 10 views

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NPTEL-Assignment
Are they view serializable or not ? S1: r1(y), r2(x), r2(y), r3(y), w2(x), w1(y), w3(x), r1(x) S2: r2(x), r3(z), w3(x), w2(x), w2(y), w3(z), r1(x), r1(y), w1(x), w1(y) S3: r1(x), r2(x), r3(y), w1(x), r2(z), r2(y), w2(y), w1(z) (Note: S1 is Conflict serialiazable hence View serializable also but I need to check directly how it VSS )

answered Oct 10 in Databases by Mk Utkarsh (153 points) | 22 views

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Self Doubt Mtech Assignments.
which of the following sequences is serializable. a) $S_a=R_1(x)R_2(x)W_1(x)R_3(x)R_4(x)W_3(x)$ b) $S_b = R_1(x)W_1(x)R_2(x)W_2(x)W_3(x)W_4(x)R_5(x)$ c) $S_c=R_1(x)W_1(x)W_2(x)R_2(x)$

answered Oct 10 in Databases by Rudr Pawan (577 points) | 15 views

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made easy (BCNF)

asked Oct 9 in Databases by altamash (41 points) | 23 views

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DBMS Ace topicwise test

answered Oct 9 in Databases by Pratyush Priyam Kuan (72 points) | 29 views

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ACE Academy Test-Series DBMS
Can someone explain, how option A can be the correct answer?

answered Oct 8 in Databases by Saurabh Pandey (45 points) | 17 views

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ACE Academy Test Series DBMS
Can someone explain this please ! I couldn’t get the correct answer.

asked Oct 8 in Databases by Rudr Pawan (577 points) | 28 views

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Madeeasy Test series
Coaching (cname, city) Travel (name, city) Select T1.name from Travel T1 where Not Exist (Select M.city FROM Coaching M where M.cname = madeeasy EXCEPT Select T2.city from Travel T2 where T1.name = T2.name) The above query returns the name of the ... city where madeeasy is located. who have not travelled in all city where madeeasy is located. N.B - This is a 1 mark question.

asked Oct 5 in Databases by MRINMOY_HALDER (32 points) | 18 views

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do we have recovery management in database in gate 2020?

asked Oct 4 in Databases by Pratyush Priyam Kuan (72 points) | 13 views

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Self Doubt on Overlapping Candidate key dependency

answered Oct 3 in Databases by GAITONDE (1.2k points) | 20 views

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3 answers

Transactions and Schedules
Consider the following schedule S T1 T2 T3 T4 Timestamp R(X) R(Y) t1 W(X) W(Y) t2 R(Y) R(X) t2 W(Y) W(X) t4 R(X) t5 W(X) t6 R(X) denotes read operation on data item X by Transcation Ti. W(X) denotes write operation on data item X by Transcation Ti. Choose the correct execution order for the above schedule S. a)T3-T2-T1-T4 b)T2-T3-T1-T4 c)T2-T4-T3-T1 d)T4-T2-T3-T1

answered Oct 1 in Databases by Mk Utkarsh (153 points) | 19 views

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Self Doubt: Relational Calculas
I am getting problem, to differentiate between these two queries $\left\{t \mid t \in \pi_{R-S} (r) \wedge \forall u \in s \left(\exists v \in r \left(u = v[S] \wedge t = v\left[R-S\right]\right )\right )\right\}$ ... Please give some example to differentiate between two, I mean what is returning by both?

asked Sep 30 in Databases by srestha (318 points) | 14 views

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DBMS_subject_test
Consider The Following Relation With Given Function Dependencies R(A,B,C,D,E,F) {A->BC,CD->E,E->C,D->AEF,ABF->BD,DF->BC} What is the number of candidate key of relation ______.

asked Sep 29 in Databases by SAMIN KHAN (7 points) | 23 views

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self_doubt_dbms
Let R1(P,Q,R) and R2(S,T) be two relation schema, where the primary keys are underline and R be a foreign key in R1 referring R2.Which of the following relational algebra expressions would necessary produce an empty relation ? 1.$\small \prod _{} R (R1)-\prod _{} S (R2)$ 2.$\small \prod _{} S (R2)-\prod _{} R (R1)$

asked Sep 29 in Databases by SAMIN KHAN (7 points) | 11 views

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#gatebook_2020test
Which of the following are legal B-trees for when the minimum branching factor ? it is right ??

asked Sep 29 in Databases by mohan123 (20 points) | 11 views

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1 answer

#GB test 2020
Consider table R with attributes A,B,C,D, and E. What is the largest number of candidate keys that R could have at the same time ?

answered Sep 27 in Databases by Satbir (2.5k points) | 28 views

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NPTEL, View Serialisability
Q7, from this assignment: https://nptel.ac.in/content/storage2/courses/106104135/assignment6.pdf S1 : r1(x),r2(x),w2(x),r3(x),w1(x), w2(y),r3(y),w3(x) S2 : r2(x),r1(x),w1(x),w2(x),w2(y),r3(x),w3(x),r3(y) Check whether they are view ... initial value. In this case, initial value of x is read by T1 in S1, while in S2, it is read by T2. So are they view equivalent or not?

asked Sep 21 in Databases by goxul (110 points) | 26 views

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Source : made easy test series DBMS
What should be the answer to this question. Also please provide the explanation for the answer.

asked Sep 21 in Databases by karanvashisht1026 (7 points) | 52 views

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SET operation in relational algebra.
Should names of attribute be same while applying SET operation in relational algebra?

asked Sep 21 in Databases by him0000 (13 points) | 10 views

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Gatebook;DBMS
Consider the relation employee(name,sex,manager) with name as the key, manager gives the name of the supervisor of the employee under consideration. What does the following Tuple Relational Calculus query produce? A. Names of employees who have a female subordinate B. ... manager How to interpret this TRC expression? The y.name = e.manager =>x.sex=female part is troublesome.

answered Sep 19 in Databases by Bikram (1.2k points) | 13 views

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Gatebook: DBMS
Consider the following table Mystery A B 1 null 2 4 3 5 null 6 select count() from Mystery where A not in( select B from Mystery) What is the output of this query? (A) 1 (B) 0 (C) 4 (D) 3

answered Sep 19 in Databases by Vimal Patel (221 points) | 13 views

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Gatebook; DBMS
In translating from an entity-relationship (E-R) diagram to a relational schema, one piece of E-R logic that cannot be captured by primary keys, uniques, and foreign keys is (A) the weak entity. (B) any ternary relationship. (C) mandatory participation for one-time occurrence (that is, with the arrow). (D) mandatory participation for many-time occurrence (that is, without the arrow).

asked Sep 19 in Databases by Sambhrant Maurya (271 points) | 8 views