Details
Description
The scanned value comes from cursor.scanned() which is not the same as the docs loaded/scanned (nscannedOjbects in explain) but is instead the indexes (entries) scanned or number of docs returned.
This can be shown easily using a covered query:
> var firstSS = db.serverStatus()
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> db.g.find({b:2},{ b:1, _id:0}).explain()
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{
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"cursor" : "BtreeCursor b_1",
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"isMultiKey" : false,
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"n" : 2,
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"nscannedObjects" : 0,
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"nscanned" : 2,
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"nscannedObjectsAllPlans" : 0,
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"nscannedAllPlans" : 2,
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...}
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> db.serverStatus().metrics.document.scanned - firstSS.metrics.document.scanned
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2
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Attachments
Issue Links
- duplicates
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SERVER-12774 "nscanned" not logged anymore for queries
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- Closed
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- is related to
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SERVER-17862 Unify stats reporting for log/profiler across CRUD operations
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- Closed
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- related to
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- Closed
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