Which of the following is correct? A. B trees are for storing data on disk and B+ trees are for main memory. B. Range queries are faster on B+ trees. C. B trees are for primary indexes and B+ trees are for secondary indexes. D. The height of a B+ tree is independent of the number of records.

GATE 1999 · Databases · B Tree · easy

Answer: B. Range queries are faster on B+ trees.

1. Evaluate option A: B trees and B+ trees are both used for disk-based storage. Option A is FALSE.
2. Evaluate option B: B+ trees link leaf nodes. A range query [lo,hi] searches for lo then scans linked leaves to hi. Much faster than B tree range scan. Option B is TRUE.
3. Evaluate options C and D: C: Both tree types can serve any index type. FALSE. D: Height depends on number of records. FALSE.