JUNE 2012 - PAPER II

10. Which command is the fastest among the following ?

(A) COPY TO
(B) COPY STRUCTURE TO
(C) COPY FILE
(D) COPY TO MFILE-DA T DELIMITED

Ans:-B

Explanation:- I am considering the same answer as what is given in the UGC answer key. I will find out why that command is supposedly faster than the rest. Give me some time. Meanwhile, i do not want to get stuck in this question and i want to proceed. So we are off to the next one but will visit the same sometime later.

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11. B+ tree are preferred to binary tree in Database because

(A) Disk capacity are greater than memory capacities
(B) Disk access is much slower than memory access
(C) Disk data transfer rates are much less than memory data transfer rate
(D) Disks are more reliable than memory

Ans:-B

Explanation:- Actually the same question was given in GATE CS(2000) paper and the solution is available in a webpage called geeksforgeeks. A good page with solutions to some gate questions. Everyone knows that disk access is slower compared to memory access. When we compare a binary tree to a B+ tree, B+ tree is supposed to have a higher fanout. What is a fanout actually?. B+ trees can store a relatively large number of pointers to child nodes in each node. Fanout means the number of pointers per node. B+ trees minimize the depth of the tree( and so one can reach the leaf node faster)by employing high fanout. That is linking many children from each node. Because of a high fanout the number of I/O operations required to find an element in the tree would be less. So B+ trees are preferred. The option is B.

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12. A Transaction Manager is which of the following ?

(A) Maintains a log of transactions
(B) Maintains before and after database images
(C) Maintains appropriate concurrency control
(D) All of the above

Ans:-D

Explanation:- Transaction manager performs all the operations mentioned in option A,B and C.

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13. Leaves of which of the following trees are at the same level ?

(A) Binary tree
(B) B-tree
(C) A VL-tree
(D) Expression tree

Ans:-B

Explanation:- In a B-tree leaves are at the same level. A B-tree of order m is an m-way tree which means that for each node there may be upto m children. m should be odd only.

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