Database Management System

Question 1
 
A
T2 must be aborted and then both T1 and T2 must be re-started to ensure transaction atomicity
B
Schedule S is non-recoverable and cannot ensure transaction atomicity
C
Only T2 must be aborted and then re-started to ensure transaction atomicity
D
Schedule S is recoverable and can ensure atomicity and nothing else needs to be done
       Database Management System       Transactions       GATE 2015(Set-03)
Question 1 Explanation: 
T2 is reading the value written by T1 and getting committed before T1 commits. So it is non-recoverable schedule.
Question 2
Consider a B+ tree in which the search key is 12 bytes long, block size is 1024 bytes, record pointer is 10 bytes long and block pointer is 8 bytes long. The maximum number of keys that can be accommodated in each non-leaf node of the tree is ____ .  
A
50
B
60
C
70
D
80
       Database Management System       B+-Trees       GATE 2015(Set-03)
Question 2 Explanation: 
Explanation: Suppose that ‘k’ is order of the non-leaf node
k(8) + (k-1)12 ≤ 1024
20k ≤1036
k ≤ ⌊1036/20⌋ ⇒ k ≤ 51
As the order is 51, maximum we can store 50 keys.
There are 2 questions to complete.