A relevance score is a number indicating how closely a search result matches a query. In Atlas Search, it helps rank matching documents: higher scores indicate closer matches. Scores are calculated dynamically and have no fixed upper limit, so read them in the context of the query rather than as percentages. section 11.5.1 section 11.8
Lucene assigns scores after matching searchable tokens. A query term appearing more often in a document can raise its score, while a term common across the collection contributes less. Token proximity and indexing settings can also affect the ranking. Boosting or decaying scores can tailor relevance to a search domain. section 11.2
To use scores in an Atlas Search aggregation:
- Start with a $search stage targeting a search index. A compound query can require several text matches, such as a business name, inspection result, and sector. section 11.5.1
- Add the score to each returned document with a subsequent stage that sets `score: { $meta: "searchScore" }`. section 11.5.1
- Sort by `score: -1` and limit the output when an application needs the highest-scoring matches first. section 11.5.1 section 13.5.1
Compare matches, not percentages
A search requiring “food” in `business_name`, “PASS” in `result`, and “127” in `sector` returns a matching inspection with a score of about 2.94. That number describes its relevance to those search criteria; it is not a score out of a fixed maximum. section 11.5.1
Listing 13.2 Executing a full-text search locally
db.inspections.aggregate([
{
$search: { #1
index: 'LocalSearchIndex', #2
text: {
query: 'No Violation Issued', #3
path: ['result', 'business_name'], #4
fuzzy: {
maxEdits: 2 #5
}
}
}
},
{
$match: { #6
sector: 'Cigarette Retail Dealer - 127', #7
'address.city': 'RIDGEWOOD' #8
}
},
{
$addFields: { #9
score: { $meta: "searchScore" }
}
},
{
$sort: { #10
score: -1
}
},
{
$limit: 3 #11
},
{
$project: { #12
_id: 0, #13
business_name: 1,
certificate_number: 1,
date: 1,
result: 1,
'address.street': 1,
'address.number': 1,
'address.zip': 1,
score: 1 #14
}
}
])
This local Atlas Search pipeline combines fuzzy text matching with filters, exposes `searchScore`, sorts descending, and returns the top three results. section 13.5.1
For a quick view of an entire result set, aggregate the scores into minimum, maximum, and average values. One filtered inspection search reports 13 matches with scores ranging from about 3.27 to 7.45. These statistics summarize that query’s matches without listing every document. section 11.5.2
