Recent questions and answers in Databases - GATE CSE Doubts

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Applied gate test
Suppose we have B-tree nodes with room for three keys and four-pointers. Suppose also that when we split a leaf, we divide the pointers 2 and 2, while when we split an interior node, the first 3 pointers go with the first (left) node, and the last 2 pointers ... in order, records with keys 4, 5, 6, and so on. At the insertion of what key will the B-tree first reach four levels?

asked 8 hours ago in Databases by Raj_81 (5 points) | 5 views

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database management systems
hi guys, if a lossless, dependency preserving relation is there, then it can be decomposed into 3NF if a lossless, dependency preserving relation is there, then it can be decomposed into bcnf which one is correct? and why?

asked 20 hours ago in Databases by rish1602 (7 points) | 5 views

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View serialisability
While checking whether a schedule is view serialisable or not. I read that if there is no blind write then schedule is not view serialisable. I am not able to figure out reason behind this.

answered 1 day ago in Databases by Shashank Rustagi (513 points) | 34 views

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self doubt araised from previous years question
if sql query does not have any tuple to return then what will it return?either null or zero

answered 5 days ago in Databases by Shashank Rustagi (513 points) | 28 views

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Made Easy Test series
Is the given answer correct? How to solve this one?

asked 6 days ago in Databases by CSHuB (13 points) | 18 views

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Deriving FD's from given FD set
Suppose two FD’s are given W ->X and W->Y can we derive by replacing left hand side attribute? Are X->Y and Y->X are also valid?

answered 6 days ago in Databases by ayush.5 (71 points) | 10 views

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made-easy relational-algebra
consider the relation R(A, B, C, D). Which relational algebra expression to return the lowest value of A?

asked Oct 21 in Databases by kalin (5 points) | 18 views

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Applied gate mock 1
Whether the given schedule is serializable or not? The given schedule is clearly not conflict serializable as precedence graph contains cycle.. But will it be view serializable or not?? I used For View Equivalence: (1) If transaction Ti reads initial value of any ... satisfied.. (if you got any violation then let me know) But the given answer says it is not view serializable..

asked Oct 21 in Databases by Verma Ashish (697 points) | 19 views

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Database Systems by Elmasri and Navathe(4th edition)

asked Oct 21 in Databases by ayush.5 (71 points) | 11 views

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Database System (4th edition) by Elmasri and Navathe. ER model to relational model conversion.

asked Oct 21 in Databases by ayush.5 (71 points) | 11 views

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Applied test series
Suppose we have a B-tree 3 nodes with room for 3 keys and 4 pointers. suppose also that when we split a leaf, we divide the pointers 2 and 2. while when we split and interior node, the first three pointers go with the first node(left node), and the last two pointers go ... ,5,6 and so on. At the insertion of what key will the B tree first reach four levels??? A:24 B:15 C:28 D:20

asked Oct 13 in Databases by Ashutosh777 (67 points) | 19 views

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Serialisability in Blind write
I read one Gate question and in Korth's book that if a schedule contains blind write then it is not conflict serialisable. I am not able to understand the reason. This is the gate question – https://gateoverflow.in/302837/gate2019-11 I also read that timestamp protocol allows conflict serializable schedules.

asked Oct 12 in Databases by vizzard110 (85 points) | 10 views

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DatabaseTransaction
what is difference between blind write and write write conflict .

answered Oct 12 in Databases by vizzard110 (85 points) | 34 views

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Serializability
Consider the following schedule: SCHEDULE: r1(P), w2(P), r3(P), r1(Q), r4(R), w2(Q), r1(S), w3(S), r4(S), w4(Q), w5(Q), w5(R) Is this given schedule conflict serializable? If yes, prepare a precedence graph and write the order of execution for transactions.

answered Oct 11 in Databases by HeartBleed (79 points) | 23 views

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made easy dbms test
no of serial schedules view equivalent to schedule S but not conflict equal to schedule S are

asked Oct 8 in Databases by Ashutosh777 (67 points) | 13 views

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ER diagram to relation table
can someone please tell me a good source to study ER model to relation table conversion. I have lots of confusion in it. where I can practice some good questions other than gate questions??

asked Oct 6 in Databases by Akanksha Agrawal (309 points) | 26 views

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Made Easy Try Yourself
Find all view equivalent serial schedule for r1(A)r2(A)r3(A)w1(B)w2(B)w3(B).

answered Oct 6 in Databases by Shashank Rustagi (513 points) | 23 views

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self doubt in dbms
Is the pattern matching used in sql case sensitive?? Ex: Like %e% & Like %E% will return the same tuples?? please provide a reference for your answer

asked Oct 5 in Databases by Ashutosh777 (67 points) | 13 views

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Made Easy Test Series
Why Option B is not right. As no multivalued attributes are allowed in tables?

asked Sep 28 in Databases by Karan01 (5 points) | 32 views

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FOURTH SEMESTER B.TECH DEGREE EXAMINATION, December 2018, APJ ABDUL KALAM TECHNOLOGICAL UNIVERSITY

asked Sep 27 in Databases by njb (5 points) | 12 views

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Gate mock exam.
Consider a database with the following schema: Person ( name, age, gender ) name is a key Frequents ( name, pizzeria ) (name, pizzeria) is a key Eats ( name, pizza ) (name, pizza) is a key Serves ( pizzeria, pizza, price ) (pizzeria, pizza) ... only pizzeria's serving at least one pizza they eat" is Reference : https://www.geeksforgeeks.org/gate-gate-cs-mock-2018-question-59/

asked Sep 20 in Databases by Kapilji (5 points) | 18 views

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DRDO CS PAPER 2008
Which of the following is impossibility? A. A sparse primary index B. A sparse secondary index C. A dense primary index D. A dense secondary index

answered Sep 13 in Databases by Ehraz Hasan (366 points) | 34 views

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Previous Gate
https://gateoverflow.in/2510/gate1994-14 For a B+ - tree of order d with n leaf nodes, the number of nodes accessed during a search is O(−) Please explain me Sachin’s answer in extra details. I cant even understand after 2 lines.

asked Sep 11 in Databases by Gupta731 (17 points) | 18 views

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Made Easy Subject Wise DBMS
Consider the following schedule: S: r1(A), r2(A), r3(A), r4(A), w1(B), w2(B), w3(B), w4(B). Find the number of all possible view-equivalent schedules. Find the number of all possible conflict-equivalent schedules. How many serializable schedules are there that are not conflict serializable.

answered Sep 11 in Databases by suvradip das (113 points) | 110 views

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Made Easy Subject Wise Database
If a relation is in BCNF surely it will be in a 4NF as well. [True or False, with explanation] Made Easy Solution : True. [I think False]

answered Sep 10 in Databases by raju6 (11 points) | 38 views

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Self Doubt Database recoverability
All conflict serializable schedules are recoverable.[True or False] Please provide the explanation as well as reference too if possible

answered Sep 10 in Databases by raju6 (11 points) | 56 views

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Made Easy DBMS
Which of the following statement is false? Relation with every attribute is prime, always in BCNF. Relation with every attribute prime always in 3NF. Relation R which satisfies 3NF and atmost one compound candidate key is also in BCNF Relation with every candidate key is ... , so as per me, Option (D) also is false, while according to Made Easy it is true, someone please clarify.

asked Sep 9 in Databases by Ollie (453 points) | 35 views

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MADE EASY TEST SERIES DBMS DOUBT ON NATURAL JOIN
Hi the doubt is: There is nothing mentioned in the question that the refrencial integrity constraint is to be followed so the minimum tables would be 1500 or 0 after natural join?

asked Sep 7 in Databases by Shashank Rustagi (513 points) | 57 views

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ACE TEST SERIES
Consider the following Relations R(IJKLMNO) With following FD’S IJ -→ K KL → M MN → O NO → M LM → K JK → I Number of candidate keys?

answered Sep 7 in Databases by Shashank Rustagi (513 points) | 45 views

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Self Doubt on Transcation & Concurrency Control
Why this schedule is not View Serializable?? Anyone please elaborate this.

asked Sep 7 in Databases by AbhayPrajapati (7 points) | 34 views

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DBMS Self doubt
Consider a concurrent schedule of two transactions $T_1, T_2$: $S: R_2(A), R_1(A), W_1(A), W_2(A)$, this schedule is not conflict serializable.However, if we follow timestamping protocol, where $TS(T_1)<TS(T_2)$ $S$ is allowed, which is contradictory to the fact that timestamping protocol gives a conflict serializable schedule. What am I missing here?

answered Sep 6 in Databases by Shashank Rustagi (513 points) | 23 views

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#self doubt #databases #normqlisation
If we decompose R(ABCDE) into 2nd normal form what all tables we get . Given FDs(A->C,C->D,D->E,C->A).

answered Sep 4 in Databases by Ehraz Hasan (366 points) | 54 views

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applied test series
The original answer says that every team participating should have exactly one refree which I think is wrong. my observations:- 1. if there is a refree then he/she needs to instruct atleast a single game 2.if there is a match btw two teams then they ... teams present that doesn't plays a match. PS-here the refree entity is in total participation please correct me if I am wrong

asked Sep 4 in Databases by Sahil91 (5 points) | 13 views

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Self Doubt - (PYQs)
https://gateoverflow.in/1485/gate1999-2-7-ugcnet-june2014-iii-25 In this question if $R_1 \cap R_2 = \phi$ then will the decomposition will be lossy but does that mean that $R_1$ and $R_2$ individually can’t be in 2NF, 3NF or BCNF?

answered Sep 2 in Databases by suvradip das (113 points) | 11 views

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SQL query where data is not in tabular form but in JSON Format

asked Sep 2 in Databases by ssurana (5 points) | 67 views

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2 answers

DBMS NPTEL assignment doubt

answered Aug 31 in Databases by suvradip das (113 points) | 35 views

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Raghu Ramkrishnan - Transactions and Concurrency Control

answered Aug 30 in Databases by Shashank Rustagi (513 points) | 55 views

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Made Easy Workbook
Please someone solve Q35.

asked Aug 28 in Databases by Mellophi (333 points) | 33 views

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ME TEST SERIES
Can anyone tell how this works?

answered Aug 28 in Databases by Akanksha Agrawal (309 points) | 28 views

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2 answers

Self doubt DBMS Conflict Equivalent schedules
$\text{Consider the transactions given below}$ What are the number of conflict equivalent schedules possible What is the approach to solve such questions T1 T2 T3 $r_{A}$ $w_{B}$ $r_{A}$ $w_{B}$ $r_{A}$ $w_{B}$

answered Aug 27 in Databases by Shashank Rustagi (513 points) | 38 views

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