ISRO-2018
January 5, 2024Question 23 – ISRO-2018
January 5, 2024ISRO-2018
| Question 12 |
In a file which contains 1 million records and the order of the tree is 100, then what is the maximum number of nodes to be accessed if B+ tree index is used?
| 5 | |
| 4 | |
| 3 | |
| 10 |
Question 12 Explanation:
Explanation:
→ If there are K search-key values in the file, the path is no longer than ⌈log⌈n/2⌉(K)⌉.
→ A node is generally the same size as a disk block, typically 4 kilobytes, and n is typically around 100 (40 bytes per index entry).
→ With 1 million search key values and n = 100, at most log50(1000000)=4 nodes are accessed in a lookup.
Note: Contrast this with a balanced binary free with 1 million search key values around 20 nodes are accessed in a lookup. Above difference is significant since every node access may need a disk I/O, costing around 20 milliseconds!
→ If there are K search-key values in the file, the path is no longer than ⌈log⌈n/2⌉(K)⌉.
→ A node is generally the same size as a disk block, typically 4 kilobytes, and n is typically around 100 (40 bytes per index entry).
→ With 1 million search key values and n = 100, at most log50(1000000)=4 nodes are accessed in a lookup.
Note: Contrast this with a balanced binary free with 1 million search key values around 20 nodes are accessed in a lookup. Above difference is significant since every node access may need a disk I/O, costing around 20 milliseconds!
Correct Answer: B
Question 12 Explanation:
Explanation:
→ If there are K search-key values in the file, the path is no longer than ⌈log⌈n/2⌉(K)⌉.
→ A node is generally the same size as a disk block, typically 4 kilobytes, and n is typically around 100 (40 bytes per index entry).
→ With 1 million search key values and n = 100, at most log50(1000000)=4 nodes are accessed in a lookup.
Note: Contrast this with a balanced binary free with 1 million search key values around 20 nodes are accessed in a lookup. Above difference is significant since every node access may need a disk I/O, costing around 20 milliseconds!
→ If there are K search-key values in the file, the path is no longer than ⌈log⌈n/2⌉(K)⌉.
→ A node is generally the same size as a disk block, typically 4 kilobytes, and n is typically around 100 (40 bytes per index entry).
→ With 1 million search key values and n = 100, at most log50(1000000)=4 nodes are accessed in a lookup.
Note: Contrast this with a balanced binary free with 1 million search key values around 20 nodes are accessed in a lookup. Above difference is significant since every node access may need a disk I/O, costing around 20 milliseconds!