In a database file structure, the search key field is 9 bytes long, the block…
2006
In a database file structure, the search key field is 9 bytes long, the block size is 512 bytes, a record pointer is 7 bytes and a block pointer is 6 bytes. The largest possible order of a non-leaf node in a B+ tree implementing this file structure is
- A.
23
- B.
24
- C.
34
- D.
44
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Correct answer: C
Given:
Search key size = 9 bytes
Block pointer size = 6 bytes
Block size = 512 bytes
For a non-leaf (internal) node with m pointers, the node stores m block pointers and m−1 keys. Therefore the space constraint is:
m × 6 + (m − 1) × 9 ≤ 512
Solve the inequality:
m×6 + (m−1)×9 ≤ 512 ⇒ 6m + 9m − 9 ≤ 512 ⇒ 15m − 9 ≤ 512
15m ≤ 521 ⇒ m ≤ 521/15 ≈ 34.733…
m must be an integer, so the largest possible order is 34.
Answer: 34
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