What is the difference between $push and $addToSet?

Updated May 1, 2026

Short answer

$push adds an element to an array; $addToSet adds it only if it doesn't already exist.

Deep explanation

$push allows duplicates and is faster. $addToSet ensures uniqueness but has a slight performance overhead due to the check.

Real-world example

Adding unique tags to a blog post.

Common mistakes

Using $push when you need unique values, leading to duplicate data entry.

Follow-up questions

How to push multiple items at once?

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