Explanation:The $project takes a document that can specify the inclusion of fields, the suppression of the _id field, the addition of new fields, and the resetting the values of existing fields. 8. Which of the following method is to verify whether MongoDB used index intersection ?
A. explain()
B. analyze()
C. intersect()
D. None of the mentioned
Answer:A
Explanation:The $project takes a document that can specify the inclusion of fields, the suppression of the _id field, the addition of new fields, and the resetting the values of existing fields. 8. Which of the following method is to verify whether MongoDB used index intersection ?
A. explain() B. analyze() C. intersect() D. None of the mentioned
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. An index prefix is a subset of a______ index, consisting of one or more keys starting from the beginning of the index.