Recent questions tagged databases / GATE Overflow for GATE CSE

Consider the following schedule:S:r1(a) r3(d) w1(B) r2(B) r4(B) w2(C) r5(C) w4(E) r5(E) w5(B)How many serial schedules conflict equal to schedules (S)?

shivangi5

1.9k views

shivangi5 asked Dec 4, 2017

2 votes

1 answer

1536

Transaction
How many concurrent schedules are conflict serializable of given transactions T1 and T2: T1 = r1(A) W1(A)R1(B)W1(B) T2 = R2(B)W2(B)R2(A)W2(A)

How many concurrent schedules are conflict serializable of given transactions T1 and T2:T1 = r1(A) W1(A)R1(B)W1(B)T2 = R2(B)W2(B)R2(A)W2(A)

sunaina rawat

842 views

sunaina rawat asked Dec 4, 2017

0 votes

0 answers

1537

MadeEasy Test Series: Databases - B Tree
Suppose size of block 1000 bytes search key of 12 bytes, pointer size 8 bytes. How many maximum records in DB file which can index by dense B+ tree of 2 levels? given ans is 2499 but I am getting 2450

Suppose size of block 1000 bytes search key of 12 bytes, pointer size 8 bytes. How many maximum records in DB file which can index by dense B+ tree of 2 levels?given ans ...

sunaina rawat

427 views

sunaina rawat asked Dec 4, 2017

0 votes

1 answer

1538

Test Series
Why not the ans is 2...please explain

Why not the ans is 2...please explain

sunaina rawat

284 views

sunaina rawat asked Dec 4, 2017

1 votes

0 answers

1539

MadeEasy Test Series: Databases - Indexing
Which of the following statement is/are true? For any data file it is possible to construct two separate sparse first level indexes on different keys. For any data file, it is possible to construct two separate dense first level indexes ... possible to construct a sparse first level index and a dense second level index,both should be useful. All the above

Which of the following statement is/are true?For any data file it is possible to construct two separate sparse first level indexes on different keys.For any data file, it...

shivangi5

630 views

shivangi5 asked Dec 4, 2017

3 votes

1 answer

1540

MadeEasy Test Series: Databases - Er Diagram
In the solution they have merged E1 R4 E4 , E2 R3 E3 R5 , R6 E5. MY DOUBT IS , why cant we only merge R4 E4 instead of E1 R4 E4. since there is total participation on the E4 side of the relation and it would also decrease the number of attributes .

In the solution they have merged E1 R4 E4 , E2 R3 E3 R5 , R6 E5.MY DOUBT IS , why cant we only merge R4 E4 instead of E1 R4 E4. since there is total participation on the ...

shaurya vardhan

1.2k views

shaurya vardhan asked Dec 4, 2017

1 votes

3 answers

1541

MadeEasy Test Series: Databases - B Tree
Which of the following statement true about B tree and B+ tree index? Assume order of B tree node same as order of B+ tree node. B tree index has more levels than B+ tree index for large number of keys. B+ tree index has more levels than B ... records. B+ tree index nodes more than B tree for large number of keys I think a is correct but the given ans is b

Which of the following statement true about B tree and B+ tree index? Assume order of B tree node same as order of B+ tree node.B tree index has more levels than B+ tree ...

shivangi5

1.9k views

shivangi5 asked Dec 4, 2017

0 votes

1 answer

1542

#DBMS SQL QUERY
Consider the table employee(empId, name, department, salary) and the two queries Q1,below. Assuming that department 5 has more than one employee, and we want to find the employees who get higher salary than anyone in the department 5, IS the QUERY (Q1) is ... IN (Select * From employee s Where s.department = "5" and s.salary >= e.salary) PLEASE EXPLAIN WITH EXAMPLE!

Consider the table employee(empId, name, department, salary) and the two queries Q1,below. Assuming that department 5 has more than one employee, and we want to find the ...

iarnav

776 views

iarnav asked Dec 4, 2017

2 votes

1 answer

1543

Relational algebra
Consider the relations r1(P, Q, R) and r2(R, S, T) with primary keys P and R respectively. The relation r1 contains 2000 tuples and r2 contains 2500 tuples. The maximum size of the join r1⋈ r2 is equal to r2⋈ r1 true or false?

Consider the relations r1(P, Q, R) and r2(R, S, T) with primary keys P and R respectively. The relation r1 contains 2000 tuples and r2 contains 2500 tuples. The maximum s...

learner_geek

1.7k views

learner_geek asked Dec 3, 2017

0 votes

0 answers

1544

Number of Table in ER
Q1 I think here number of tables required should be 2 right? Q2 Consider the following set of functional dependencies { (Eid, pno) --> hours, Eid --> Ename, Pno --> (Pname, Plocation), Pname --> Plocation } in a relation R ( ... in an entity It can be derived from a different entity All of the above. Here answer is 4. Any good reference to support answer?

Q1I think here number of tables required should be 2 right?Q2 Consider the following set of functional dependencies{(Eid, pno) hours,Eid Ename,Pno (Pnam...

Shubhanshu

299 views

Shubhanshu asked Dec 3, 2017

2 votes

3 answers

1545

relational algebra
Consider the following schema: Student (Sid, Sname, age) Course Info (Cid, Cname, Instructor SSN) Enroll (Sid, Cid, grade). The relational algebra expression for “find the Cid’s of courses enrolled by two different students” (no options)

Consider the following schema:Student (Sid, Sname, age)Course Info (Cid, Cname, Instructor SSN)Enroll (Sid, Cid, grade). The relational algebra expression for “find the...

shaurya vardhan

6.1k views

shaurya vardhan asked Dec 3, 2017

1 votes

0 answers

1546

Number of Super keys
Q1) Consider the relation with n attributes if any 2 attribute is a candidate key, then the total number of candidate keys are___ ? Then what will be the generalized formula I) $\sum_{i=2}^{n}C(n,i)$ II) $\sum_{i=2}^{n}C(n,i)*C(i,2)$ ... then ABE is a single superkey. So which one is correct? Q2) Is the answer remains same if use every in place of any in above question?

Q1) Consider the relation with n attributes if any 2 attribute is a candidate key, then the total number of candidate keys are___ ?Then what will be the generalized formu...

Shubhanshu

771 views

Shubhanshu asked Dec 3, 2017

0 votes

1 answer

1547

#DBMS SQL
Consider the following relations A, B and C: A Id Name Age 12 Arun 60 15 Shreya 24 99 Rohit 11 B Id Name Age 15 Shreya 24 25 Hari 40 98 Rohit 20 99 Rohit 11 C Id Phone Area 10 2200 02 99 2100 01 How many tuples does the result of the following SQL queryS contain? 1) SELECT ... WHERE B.Name = Arun') 3) SELECT A.Id FROM A WHERE A.Age > NOT ALL (SELECT B.Age FROM B WHERE B.Name = Arun')

Consider the following relations A, B and C: AIdNameAge12Arun6015Shreya2499Rohit11 BIdNameAge15Shreya2425Hari4098Rohit2099Rohit11 CIdPhoneArea1022000299210001How man...

iarnav

1.1k views

iarnav asked Dec 2, 2017

2 votes

2 answers

1548

#dbms relational algebra
Consider the following relations A, B and C: A Id Name Age 12 Arun 60 15 Shreya 24 99 Rohit 11 B Id Name Age 15 Shreya 24 25 Hari 40 98 Rohit 20 99 Rohit 11 C Id Phone Area 10 2200 02 99 2100 01 How many tuples does the result of the following relational algebra expression contain? Assume that the schema of A∪B is the same as that of A. (A∪B)⋈A.Id>40∧C.Id<15C

Consider the following relations A, B and C: AIdNameAge12Arun6015Shreya2499Rohit11 BIdNameAge15Shreya2425Hari4098Rohit2099Rohit11CIdPhoneArea1022000299210001How many tupl...

iarnav

829 views

iarnav asked Dec 2, 2017

1 votes

0 answers

1549

#dbms query
how to read/breakdown/understand this query? which part wil be solved first? {t∣t∈πR−S(r)∧∀u∈s(∃v∈r(u=v[S]∧t=v[R−S]))}

how to read/breakdown/understand this query? which part wil be solved first?{t∣t∈πR−S(r)∧∀u∈s(∃v∈r(u=v[S]∧t=v[R−S]))}

iarnav

314 views

iarnav asked Dec 2, 2017

0 votes

1 answer

1550

#DBMS QUERY
WHAT DOES THIS MEAN- πR−S,S(r) PLEASE EXPLAIN WITH EXAMPLE; HOW TO PROJECT VALUES IN THIS CASE (ASSUME TABLE ON YOUR OWN). attributes in R(a,b,c) attributes in S(c)

WHAT DOES THIS MEAN-πR−S,S(r)PLEASE EXPLAIN WITH EXAMPLE; HOW TO PROJECT VALUES IN THIS CASE (ASSUME TABLE ON YOUR OWN).attributes in R(a,b,c)attributes in S(c)

iarnav

507 views

iarnav asked Dec 2, 2017

3 votes

1 answer

1551

ER MODEL
What is the relationship between strong entity and weak entity 1:1 1:M M:1 M:N Please explain ?

What is the relationship between strong entity and weak entity1:11:MM:1M:NPlease explain ?

sunaina rawat

673 views

sunaina rawat asked Dec 2, 2017

1 votes

0 answers

1552

Nmber of relation in 2NF
Question asked to find minimum number of tables required. My question is how can we decide the table's unless cardinality ratio is given ?

Question asked to find minimum number of tables required.My question is how can we decide the table's unless cardinality ratio is given ?

junaid ahmad

245 views

junaid ahmad asked Dec 1, 2017

1 votes

1 answer

1553

Dbms normalization
https://gateoverflow.in/?qa=blob&qa_blobid=11537552088967137608

https://gateoverflow.in/?qa=blob&qa_blobid=11537552088967137608

Harikesh Kumar

473 views

Harikesh Kumar asked Dec 1, 2017

1 votes

0 answers

1554

MadeEasy Test Series: Databases - Transactions
Deadlock prevention(wait-kill && wound-wait) is free from both starvation as well as deadlock? True or false?

Deadlock prevention(wait-kill && wound-wait) is free from both starvation as well as deadlock?True or false?

learner_geek

382 views

learner_geek asked Dec 1, 2017

1 votes

0 answers

1555

MadeEasy Subject Test: Databases - Transactions
In below schedule (S) it has cascading abort or not?

In below schedule (S) it has cascading abort or not?

learner_geek

448 views

learner_geek asked Dec 1, 2017

1 votes

0 answers

1556

Multivalued Dependency
Can anyone please explain it ?

Can anyone please explain it ?

ankitgupta.1729

1.5k views

ankitgupta.1729 asked Nov 30, 2017

1 votes

1 answer

1557

B+ tree
Assume a system has following parameters to construct a B+ tree. The specification of the tree are: • Size of search key is 15 B • Size of block is 512 B • Size of record pointer is 9 B • Size of block pointer is 8 B The maximum number of keys that can be accommodated in each non-leaf node of the tree is ________.

Assume a system has following parameters to construct a B+ tree. The specification of the tree are:• Size of search key is 15 B• Size of block is 512 B• Size of rec...

Tuhin Dutta

791 views

Tuhin Dutta asked Nov 30, 2017

0 votes

0 answers

1558

Multivalued Dependency
Can anyone please explain how to check Multivalued Dependency ?

Can anyone please explain how to check Multivalued Dependency ?

ankitgupta.1729

349 views

ankitgupta.1729 asked Nov 29, 2017

0 votes

0 answers

1559

Test series

Nau1994

269 views

Nau1994 asked Nov 29, 2017

0 votes

1 answer

1560

Sql query
Please explain below query step by step and what does it mean?

Please explain below query step by step and what does it mean?

learner_geek

519 views

learner_geek asked Nov 29, 2017

tags	tag:apple
author	user:martin
title	title:apple
content	content:apple
exclude	-tag:apple
force match	+apple
views	views:100
score	score:10
answers	answers:2
is accepted	isaccepted:true
is closed	isclosed:true