Answer
MongoDB can only use the initial fields of a compound index. If a query does not include the prefix field, the index cannot be used.
Quick Answer
Index prefix means a compound index {a, b, c} supports queries on {a}, {a, b}, or {a, b, c} but NOT on {b} or {c} alone. MongoDB can only use a compound index from the leftmost field forward. If you frequently query by {b} alone, you need a separate index. Designing indexes with the right field order avoids creating redundant indexes.
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.
Want to bookmark, take notes, or join discussions?
Sign in to access all features and personalize your learning experience.
Source: SugharaIQ