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The ______ index is unique and prevents clients from inserting two documents with the same value for the _id field.

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+1 vote
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in MongoDB by (131k points)
The ______ index is unique and prevents clients from inserting two documents with the same value for the _id field.

(a) _id

(b) $default

(c) _def

(d) None of the mentioned

This question was addressed to me during an interview for a job.

Origin of the question is Indexes In MongoDB topic in portion Index/Indexing Concepts of MongoDB

1 Answer

+1 vote
by (652k points)
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Best answer
Correct answer is (a) _id

The best I can explain: All MongoDB collections have an index on the _id field that exists by default.

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