ITPEC FE Morning April 2021 Question 28
ITPEC FE Morning April 2021 — Question 28 of 80
Hash Index vs B+ Tree Index — choose the right index type for the query pattern.
Hash index supports only exact-match lookups (=). B+ tree index supports exact match, range queries, partial matches, and ordering.
Why (d) is correct:
- Searching by user ID = '1001' is a pure equality search → hash index is ideal
Why not others:
- (a) sales amount >= 100 — range search → requires B+ tree
- (b) product name beginning with 'DB' — prefix match (LIKE) → requires B+ tree
- (c) sales date in current month — range search (date range) → requires B+ tree
Key rule: Hash index → equality only (=). Any comparison, range, or pattern match → B+ tree.
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