Explanation: Without indexes, MongoDB must perform a collection scan. 3. MongoDB supports the creation of user-defined ascending/descending indexes on a ______ field of a document.
A. Single
B. Non Unique
C. Compound
D. None of the mentioned
Answer:A
Explanation: Without indexes, MongoDB must perform a collection scan. 3. MongoDB supports the creation of user-defined ascending/descending indexes on a ______ field of a document.
A. Single B. Non Unique C. Compound D. None of the mentioned
Explanation:If applications do not specify a value for _id the driver or the mongod will create an _id field with an ObjectId value. 4. The ______ index is unique and prevents clients from inserting two documents with the same value for the _id field.