When passing a $comment in a query count() doesn't use an index.
Testcase:
> for (var i=0; i < 1000000; i++) db.test.insert({a:i}) > db.test.count() 1000001 > db.test.count({$comment:"A"}) 1000001 > var start = new ISODate(); db.test.count(); new ISODate() - start 0 > var start = new ISODate(); db.test.count({$comment:"A"}); new ISODate() - start 155
- is duplicated by
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SERVER-25830 $comment on an empty query causes a collection scan
- Closed