Recent questions and answers in Databases - GATE CSE Doubts

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1 answer

self-doubt->ISOLATION AND CONSISTENCY
Which of the following is true? In ACID properties for transaction. 1>isolation->consistency 2>consistency->isolation

answered 3 hours ago in Databases by Vimal Patel (387 points) | 7 views

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Self doubt-transaction-dirty read
Initial value of A=6. T1 T2 R(A) A=A-2 W(A) R(A) A=A-3 W(A) commit; abort; for the above two transaction what will be the final value of A, after the above 2 are executed.

asked 6 hours ago in Databases by Doraemon (89 points) | 7 views

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self doubt-expressive power of languages
Suppose we have safe expession and aggregate function. Is the expressive power of tuple relational calculus,domain relation calculus and relational algebra same if the above 2 conditions are there? I know that the expressive power of TRC,DRC AND ... and aggregate function. But in korth it is written that TRC can be extended to support aggregation.(pg-244)

asked 7 hours ago in Databases by Doraemon (89 points) | 2 views

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Madeeasy Test Series 2020 DBMS
Consider the following schedule which involves three transaction: T1 T2 T3 R(X) R(Y) R(Y) W(X) W(X) R(Z) W(X) Assume the time stamp of transactions are (5,2,4) respectively. Which of the above statement is true about the ... schedule is allowed under Thomas write rule but not basic time stamp. The schedule is not allowed under basic time stamp and Thomas write rule.

asked 12 hours ago in Databases by scholaraniket (6 points) | 6 views

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self doubt databases
what is a compound candidate key ?is it the same as composite key ? please cite an example ..

asked 1 day ago in Databases by TUSHAR_BHATT (17 points) | 5 views

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made easy single subject DBMS
can anyone tell how the answer is 3 thank you

asked 2 days ago in Databases by Pratyush Priyam Kuan (392 points) | 12 views

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Ace Test series DBMS Grand Test
Can anyone tell how the answer is 10 thank you

asked 2 days ago in Databases by Pratyush Priyam Kuan (392 points) | 5 views

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Made easy test series : Transactions
Please give answer for above Question.

asked 2 days ago in Databases by vishal burnwal (57 points) | 8 views

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madeeasy databases
Consider a relation with following functional dependencies R(a, b, c, d) F = (ab -> cd ,ac->bd) Number of following relation schemas might be the result of BCNF normalization preserving both functional dependency and lossless join is 1)R(a, b, c) and R(a,b,d) 2)R (a, b). R(a,c) and R(c,b). 3) R(a, b, c, d) please explain if 1) is dependency preserving decomposition ?

asked 3 days ago in Databases by TUSHAR_BHATT (17 points) | 11 views

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1 answer

GO test: DBMS
https://gateoverflow.in/147564/test-by-bikram-2017-database-systems-test-2-26 Assume that a data file contains 2000 records that are ordered by a key attribute K , and a primary index on attribute K is built. The size of key is 5B and block pointer is 5B ... Last level will contain only 1 record So total number of access = 1(access for record in database file) + 3(accesses in indexes)

answered 3 days ago in Databases by srestha (558 points) | 57 views

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Loop joins DBMS
Can anyone explain with some example how to calculate no of seeks in different types of joins like Block level Nested loop Join,Nested loop Join,Merge Join etc ?

asked 3 days ago in Databases by Shivateja MST (67 points) | 10 views

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GO TEST: Test by Bikram 2017: Database Systems Test 2-17

asked 3 days ago in Databases by !KARAN (159 points) | 6 views

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SELF DOUBT (TRANSACTION)
What is the difference between number of schedules which are conflict equal to S and number of serial schedules which are conflict equal to S? Can anybody show an example of the same ? This is very confusing.

answered 5 days ago in Databases by Shaik Masthan (493 points) | 14 views

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SELF DOUBT(DBMS)
Is multiple granularity lock of dbms in syllabus? If yes,from where should i learn it?

asked 5 days ago in Databases by chandrikabhuyan8 (117 points) | 3 views

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Dependency Preserve-DBMS-ACE
Relation R(ABCDE) with FD set $F=\left \{ A\rightarrow BC,C\rightarrow DE,D\rightarrow E \right \}$ and decomposition are $R1\left ( ABCD \right )$ and $R2\left ( DE \right )$ Now my question is $C\rightarrow DE$ dependency preserved? ... $D\rightarrow E$ these two dependencies preserving and that is why $C\rightarrow DE$ also preserving. Is it true?

asked 6 days ago in Databases by srestha (558 points) | 7 views

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ACE-DBMS(SQL)
EMPLOYEE(Fname,Lname,Ssn,Bdate,Address,Sex,Salary,SuperSsn,Dnum) WORKS_ON(ESsn,Pno,Hours) PROJECT(Pname,Pnumber,Plocation,Dnum) Retrieve Name of each Employee who works on all the Project controlled by department number 5 Which of the following is correct? A) ... Select ESsn from Works_On Bwhere B.Pno=All(Select Pnumber from Project where Dnum=5)); Which option is correct and why?

asked 6 days ago in Databases by srestha (558 points) | 9 views

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DBMS doubt Calculus
In result of Tuple Relational Calculus or Domain Relational calculus is it true that duplicates are not allowed? How can this be assumed ? Anyone please clarify.

asked 6 days ago in Databases by Shivateja MST (67 points) | 6 views

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1 answer

Indexing-ACE
Consider a disk with block size 1024B. A block pointer is 6 B long. A file has 30000 employee record of fixed length and each record has 100B. Assume that an unspanned organization is used.to store records. and key SSN takes 9B.Suppose that the file is ordered by key SSN ... done $\frac{3000}{15}=200$ and then $\log200=8$ , as it is primary indexing. But they gave only 3000 But why?

answered Dec 4 in Databases by Mk Utkarsh (302 points) | 37 views

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ME Test Series (Doubt in s2pl)
Ans given is both are right but i have read that conservative is deadlock free only and other 2pl can avoid only cascading rollbacks but in stackoverflow it is shown that S2pl is deadlock free so i am confused which is right .

asked Dec 4 in Databases by vijay kumar 2 (15 points) | 16 views

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Made easy test series: SQL
For above question my doubt is that how can query 1st can be correct because it may give same supplier name two times if he had submitted more than one ‘Harvest’ brand item. Plz clear my doubt.

asked Dec 3 in Databases by vishal burnwal (57 points) | 14 views

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Virtual GATE-DBMS
Select the relational expression , which could possibly return following result: a c 1 2 2 3 $A)$ $\pi _{a<c}\left ( \pi _{a,c}R \right )$ $B)$ $\sigma _{a<c}\left ( \pi _{a,c}R \right )$

asked Dec 2 in Databases by srestha (558 points) | 11 views

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1 answer

ACE FULL LENGTH MOCK TEST 2 Q30
i think not equal operator is not used properly so ans should be D , plz confirm this doubt

answered Dec 1 in Databases by Priyansh Singh (122 points) | 17 views

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Made Easy Test Series 2020: DBMS
It retrieves employees whose age is greater than 20 and work for all projects named data science. It retrieves employees whose age is greater than 20 and work for some project named data science It retrieves employees whose age is greater than 20 and work for ... 'm getting B but they've given A as answer. Can anyone please verify if A is correct? If yes then how?

asked Nov 29 in Databases by Sambhrant Maurya (290 points) | 12 views

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Made easy practice book 2019
Suppose we have a block addressable disk drive. With such block organized disk non data overhead of subblocks and interblock gaps have to be accounted for. There are 40000 bytes per track and the amount of space taken up by subblocks and interlocks gaps ... bytes to be stored on disk. if a total 32 blocks can be stored per track then what is the blocking factor? [closed]

asked Nov 29 in Databases by Jyoti Kumari97 (18 points) | 10 views

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1 answer

ACE Test Series Test 40 Q18 DBMS
Ans is 30. How to solve it

answered Nov 28 in Databases by Satbir (3.7k points) | 12 views

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1 answer

ACE Test Series Test 40 Q16 DBMS
Ans is B. How do I solve it. Thank you.

answered Nov 28 in Databases by Satbir (3.7k points) | 13 views

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Self doubt: Database (Gate2019-11)
This statement came in GATE2019 $S:$ Timestamp-ordering concurrency control protocol with Thomas' Write Rule can generate view serializable schedules that are not conflict serializable: $\checkmark$ ... it will either fall under CS or VS Pleas correct me if something is going wrong from my side. Thanks. [closed]

asked Nov 27 in Databases by Kushagra गुप्ता (155 points) | 23 views

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ACE FULL LENGTH
In this question why A is also in 3NF , is this question correct ??

asked Nov 26 in Databases by Shawn Frost (29 points) | 10 views

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Self doubt: DBMS
Plz someone tell me In this question https://gateoverflow.in/39550/gate2016-2-22 how option D) incorrect? exclusive locks to O1,…,Ok in increasing order of their addresses. of this question saying, increasing order of address in lock, can ensure serializability, but it violates here. Moreover, why BFS is wrong?

answered Nov 26 in Databases by toxicdesire (170 points) | 38 views

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2 answers

ACE Test Series DBMS Questions
Anyone please respond what would be the correct answer?

answered Nov 26 in Databases by Satbir (3.7k points) | 39 views

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ACE Test Series DBMS
Anyone please reply what would be the correct Answer? [closed]

asked Nov 26 in Databases by Shivateja MST (67 points) | 9 views

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1 answer

Database superkey key
R(A,B,C,D,E)={$A\rightarrow B,B\rightarrow C,C\rightarrow A,D\rightarrow E ,E\rightarrow D$} maximum possible superkey of R

answered Nov 26 in Databases by Satbir (3.7k points) | 30 views

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Database minimal cover
Q.R(A,B,C,D,E,F,G) ={$AC\rightarrow G,D\rightarrow EG,BC\rightarrow D,CG\rightarrow BD,ACD\rightarrow B,CE\rightarrow AG$} The number of different minimal cover possible are_______.

asked Nov 25 in Databases by amit166 (113 points) | 8 views

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#database b+tree questions
Q.The following key value are inserted into b+- tree in which order of the internal node is 4 ,that of the leaf node 3 in the sequence given below .the order of internal node is the maximum number of tree pointer in each node and the order of leaf ... 50,15,30,40,35,20,8,10,5 The maximum number of times node would get split up as a result of these insertion is_______.

asked Nov 25 in Databases by amit166 (113 points) | 15 views

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ACE Test Series 54 DBMS View Serializability
Is there any trick/shortcut to check whether a schedule is view serializable? Because checking by brute force with all combinations will be time consuming. Any help is appreciated. Thank you.

asked Nov 25 in Databases by DukeThunders (288 points) | 31 views

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ACE Test Finding 3NF relations
How to solve this? Thanks.

asked Nov 25 in Databases by DukeThunders (288 points) | 8 views

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#database minimal cover questions
$FD set:{AB\rightarrow C,C\rightarrow A,BC\rightarrow D,ACD\rightarrow B,BE\rightarrow C,EC\rightarrow FA,CF\rightarrow BD,D\rightarrow E}$ Minimal cover given FD and minimal cover are unique are not for a FD set?

asked Nov 25 in Databases by amit166 (113 points) | 9 views

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1 answer

Applied Course test series:Transactions
Plz explain how can we solve above question?

answered Nov 24 in Databases by Winner (69 points) | 27 views

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Applied course test series: ER Diagram 2
Can someone plz give answer and explaination? [closed]

asked Nov 24 in Databases by vishal burnwal (57 points) | 36 views

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Applied course test series: ER Diagram 3
Can anyone plz explain and give answer?

asked Nov 24 in Databases by vishal burnwal (57 points) | 30 views

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