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Assigned Teams:

Query Execution
Operating System:
ALL
Steps To Reproduce:
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Create a replica set.

use mydb; db.coll.createIndex({a:1}); db.coll.insert({a:1}) db.coll.insert({a:false}) db.coll.insert({a: ""}) db.coll.find({a:{$gte:1}}).explain("allPlansExecution"); // keysExamined = 1 db.coll.find({a: {$in:[1, 2]} }).explain("allPlansExecution"); // keysExamined = 2

The above two queries should scan 2 documents：

{a:1}

and

{a: ""}

But the single interval query will only show keysExamined as 1.
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Create a replica set. use mydb; db.coll.createIndex({a:1}); db.coll.insert({a:1}) db.coll.insert({a:false}) db.coll.insert({a: ""}) db.coll.find({a:{$gte:1}}).explain("allPlansExecution"); // keysExamined = 1 db.coll.find({a: {$in:[1, 2]} }).explain("allPlansExecution"); // keysExamined = 2 The above two queries should scan 2 documents： {a:1} and {a: ""} But the single interval query will only show keysExamined as 1.

When using a single interval query, the number of scanned keys displayed by explain is inaccurate.

If the traversed data no longer meets the requirements , and the returned kv is empty code.

keysExamined will not increase. code

But multi-range queries use other methods to check bounds code

keysExamined data can be counted correctly.

Participants:: [DO NOT USE] Backlog - Query Execution, Chao Yin, Kyle Suarez