Create an Index

Ask MongoDB how it answered a query for one product, and it reports that it read every document in the collection to find one:

db.products.find({ name: "Banana" }).explain("executionStats")

// Output, trimmed
winningPlan: { stage: 'COLLSCAN', filter: { name: { '$eq': 'Banana' } }, direction: 'forward' }
nReturned: 1
totalKeysExamined: 0
totalDocsExamined: 5

That result comes from this small collection, which the rest of the lesson uses. To run the commands yourself, insert these documents first:

db.products.insertMany([