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 ?
A. 2dsphere
B. 2d
C. geoHaystack
D. All of the mentioned
Answer:A
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 ?
A. 2dsphere B. 2d C. geoHaystack D. All of the mentioned
Explanation:2dsphere (version 2), 2d, geoHaystack, and text indexes are always sparse. Sanfoundry Global Education & Learning Series – MongoDB.