Explanation:To determine if MongoDB used index intersection, run explain(); the results of explain() will include either an AND_SORTED stage or an AND_HASH stage. 9. You may not specify a unique constraint on a ______ index.
A. Hashed
B. Unique
C. sparse
D. compound
Answer:A
Explanation:To determine if MongoDB used index intersection, run explain(); the results of explain() will include either an AND_SORTED stage or an AND_HASH stage. 9. You may not specify a unique constraint on a ______ index.
A. Hashed B. Unique C. sparse D. compound
Explanation:Because of the unique constraint, MongoDB will only permit one document that lacks the indexed field. 10.Which of the following indexes are always sparse ?