GATE CSE 2007 | GATE CSE Year Wise Previous Years Questions

GATE CSE 2007

MCQ (Single Correct Answer)

-0.6

Consider the B⁺ tree in the adjoining figure, where each node has at most two keys and three links. GATE CSE 2007 Database Management System - File Structures and Indexing Question 13 English 1

GATE CSE 2007 Database Management System - File Structures and Indexing Question 13 English 1

Keys K 15 and then K 25 are inserted into this tree in that order. Exactly how many of the following nodes (disregarding the links) will be present in the tree after the two insertions?

GATE CSE 2007

MCQ (Single Correct Answer)

-0.6

Consider the B⁺ tree in the adjoining figure, where each node has at most two keys and three links. GATE CSE 2007 Database Management System - File Structures and Indexing Question 12 English 1

GATE CSE 2007 Database Management System - File Structures and Indexing Question 12 English 1

Now the key K 50 is deleted from the B⁺ tree resulting after the two insertions made earlier. Consider the following statements about the B⁺ tree resulting after this deletion.

i) The height of the tree remains the same.

ii) The node GATE CSE 2007 Database Management System - File Structures and Indexing Question 12 English 2 (disregarding the links) is present in the tree.

iii) The root node remains unchanged (disregarding the links).

Which one of the following options is true ?

Statements (i) and (ii) are true

Statements (ii) and (iii) are true

Statements (iii) and (i) are true

All the statements are false

GATE CSE 2007

MCQ (Single Correct Answer)

-0.6

Consider the following two transactions: T₁ and T₂.

T₁: read (A);                  T₂: read (B);
    read (B);                      read (A);
    if A = 0 then B ← B + 1;       if B ≠ 0 then A ← A - 1;
    write (B);                     write (A);

Which of the following schemes, using shared and exclusive locks, satisfy the requirements for strict two phase locking for the above transactions?

S1 : lockS(A); 	        S2 : lockS(B);
     read (A);               read (B);
     lockS(B);               lockS(A);
     read (B);               read (A);
     if A = 0                if B ≠ 0
     then B ← B + 1;        then A ← A - 1;
     write (B);              write (A);
     commit;                 commit;
     unlock (A);             unlock (B);
     unlock (B);             unlock (A);

S1 : lockX(A);          S2 : lockX(B);
     read (A);               read (B);
     lockX(B);               lockX(A);
     read (B);               read (A);
     if A = 0                if B ≠ 0
     then B ← B + 1;        then A ← A - 1;
     write (B);              write (A);
     unlock (A);             unlock (A);
     commit;                 commit;
     unlock (B);             unlock (A);

S1 : lockS(A);           S2 : lockS(B);
     read (A);                read (B);
     lockX(B);                lockX(A);
     read (B);                read (A);
     if A = 0                 if B ≠ 0
     then B ← B + 1;         then A ← A - 1;
     write (B);               write (A);
     unlock (A);              unlock (B);
     commit;                  commit;
     unlock (B);              unlock (A);

S1 : lockS(A);           S2 : lockS(B);
     read (A);                read (B);
     lockX(B);                lockX(A);
     read (B);                read (A);
     if A = 0                 if B ≠ 0
    then B ← B + 1;        then A ← A - 1;
     write (B);               write (A);                                                                                                     
     unlock (A);              unlock (A);
     unlock (B);              unlock (B);
     commit;                  commit;

GATE CSE 2007

MCQ (Single Correct Answer)

-0.6

Consider the following schedules involving two transactions. Which one of the following statements is TRUE?

S₁: r₁(X); r₁(Y); r₂(Y); r₂(X); w₂(Y); w₁(X);

S₂: r₁(X); r₂(X); r₂(Y); w₂(Y); r₁(Y); w₁(X);

Both S₁ and S₂ are conflict serializable.

S₁ is conflict serializable and S₂ is not conflict serializable.

S₁ is not conflict serializable and S₂ is conflict serializable.

Both S₁ and S₂ are not conflict serializable.

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