🧠Should You Index removed and dupSlug in MongoDB? Probably Not.Adam C. |
If you're using a full-text search with MongoDB and filtering out soft-deleted or duplicate records using fields like removed: { $exists: false } and dupSlug: { $exists: false }, you might wonder: should I index those fields for performance?
🚫 The Short Answer: No, you don't need to.
Why?
MongoDB applies $text search first, using your defined text index (e.g., SearchSwimmerByNameTeamLsc). This is handled efficiently with IXSCAN and TEXT_MATCH.
Filters like removed and dupSlug are applied later, during the FETCH stage. At that point:
MongoDB has already narrowed down the candidates using the text index.
It only needs to examine a small number of documents — for example, around ~2,865 in our case — which is very fast.
Indexing removed or dupSlug won’t help, because:
$exists: false conditions cannot use sparse indexes (they only work with $exists: true).
MongoDB doesn't allow combining $text with other fields in compound indexes.
You could create a partial index, but that only helps if you're querying those fields independently of text search.
✅ Summary
Your query is already efficient and does not require additional indexes on removed or dupSlug.
Indexing them would add storage and write overhead with no gain in performance.
Only consider indexing if:
You start querying these fields without full-text search, or
You refactor your logic to use something like isActive: true (which is easier to index).
Still seeing performance issues? You might benefit from replacing $exists: false with a flag field (isDeleted, isDuplicate) that defaults to true and can be indexed cleanly.
Let me know if you want to explore that option or review your actual query plans.