Which one of the following is used to represent the supporting many-one relationships of a weak entity set in an entity-relationship diagram?
A
Rectangles with double/bold border
B
Diamonds with double/bold border
C
Ovals that contain underlined identifiers
D
Ovals with double/bold border
2
GATE CSE 2020
MCQ (Single Correct Answer)
+2
-0.67
Consider a relational table R that is in 3NF, but not in BCNF. Which one of the following statements is TRUE?
A
A cell in R holds a set instead of an atomic value.
B
R has a nontrivial functional dependency X $$ \to $$ A, where X is not a superkey and A is a non-prime attribute and X is not a proper subset of any key
C
R has a nontrivial functional dependency X $$ \to $$ A, where X is not a superkey and A is a non-prime attribute and X is a proper subset of some key.
D
R has a nontrivial functional dependency X $$ \to $$ A, where X is not a superkey and A is a prime attribute.
3
GATE CSE 2020
MCQ (Single Correct Answer)
+2
-0.67
Consider a schedule of transactions T1 and T2 :
Here, RX stands for “Read(X)” and WX stands for “Write(X)”. Which one of the following schedules is conflict equivalent to the above schedule?
A
B
C
D
4
GATE CSE 2020
Numerical
+2
-0.67
Consider a database implemented using B+ tree for file indexing and installed on a disk drive with block size of 4 KB. The size of search key is 12 bytes and the size of tree/disk pointer is 8 bytes. Assume that the database has one million records. Also assume that no node of the B+ tree and no records are present initially in main memory. Consider that each record fits into one disk block. The minimum number of disk accesses required to retrieve any record in the database is ______.
