Explanation:MongoDB stores all data in documents, which are JSON-style data structures composed of field-and-value pairs. 3. Which of the field is reserved for use as a primary key ?
A. _id
B. _uid
C. _uuid
D. All of the mentioned
Answer:A
Explanation:MongoDB stores all data in documents, which are JSON-style data structures composed of field-and-value pairs. 3. Which of the field is reserved for use as a primary key ?
A. _id B. _uid C. _uuid D. All of the mentioned
Explanation:ID value value must be unique in the collection, is immutable, and may be of any type other than an array. 4. User-defined indexes on multiple fields is called :