Adding Lookup Data to the Aggregation Pipeline: Test your skills

You are building an aggregate statement in the Aggregation Editor. You plan to add a stage to the pipeline that inserts a new field. The field will add the values in two existing fields together to find their sum. Which aggregate operator should you use?

You are building an aggregate statement in the Aggregation Editor. The third stage is based on the $project operator. What is the name of the tab used to edit the operator’s expression?

You are building an aggregate statement in the Aggregation Editor. You plan to add a stage to the pipeline that retrieves data from a secondary collection in the same database as the primary collection. Which aggregate operator should you use for the new stage?

You are building an aggregate statement in the Aggregation Editor. The statement is based on the customers collection. You are adding a $lookup stage to the pipeline to retrieve data from the population collection, which is in the same database as the customers collection. The city field in the customers collection maps to the city_name field in the population collection. You plan to assign the name city_data to the lookup array. How do you configure the operator’s expression?

You are building an aggregate statement in the Aggregation Editor. You plan to add a stage to the pipeline that replaces an existing field with the same values but converts them from strings to integers. Which aggregate operator should you use for the new stage?

You are building an aggregate statement in the Aggregation Editor. You plan to add a stage to the pipeline that replaces an existing field with the same values but converts them from strings to integers. However, you must first remove the commas from the string values. Which operator can you use to remove the commas?

You are building an aggregate statement in the Aggregation Editor. The aggregated data includes the <population field, which provides the population for each city, and the sales field, which provides the number of sales for each city. You now want to add a field to the pipeline that shows the ratio between the number of sales and the city’s population. For this stage, you plan to use the $set operator and name the new field ratio. How should you configure the operator’s expression?

You are building an aggregate statement in the Aggregation Editor. The data returned by the pipeline provides the total number of transactions for each country in the European Union. The documents are sorted by the number of transactions, in descending order. You plan to add one more stage to the pipeline that uses the $limit operator to return the five documents with the highest transactions. Which argument should you pass in as the operator’s expression?