Lesson 7 Chapter 2 : Sorting with Indexes

Hi mongodb community,

In minute 2:41, kirby create an explanaible object and exucute a query using ssn field for sorting :

Then he finds the total key examined and total doc returned in executions stats :

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For me, I have to create first an index on ssn field before executing this query. Otherwise 0 key is examined .There is no indication in the video lesson to create first an index on ssn field

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After creating index on ssn field :

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What do you think ?

thanks

Best regards
Otmane