Answer
Hidden indexes allow evaluating the impact of index removal without affecting the planner, useful for safe index tuning.
Quick Answer
Hidden indexes are maintained but not used by the query planner. You can hide an index to test the performance impact of removing it without actually dropping it. If queries stay fast, the index was unused and you can safely drop it. If performance degrades, unhide it. Introduced in MongoDB 4.4 to safely evaluate index removal in production.
S
SugharaIQ Editorial Team
Verified Answer
This answer has been peer-reviewed by industry experts holding senior engineering roles to ensure technical accuracy and relevance for modern interview standards.
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Source: SugharaIQ