Consider that you have a collection called population which has fields state and city. Which of the following query will calculate the population grouped by state and city?

What tool do you use to see if you have a problem in the consumption of disk I / 0?

Consider a collection posts which has fields: Jd, post_text, post_author, post_timestamp, post_tags etc. Which of the following query retrieves ONLY the key named post_text from the first document retrieved?

Consider that our posts collection contains an array field called tags that contains tags that the user enters. {

Which of the following commands will find all the posts that have been tagged as tutorial.

In what format does mongodump creates backup files?