{$ne: null} has some counterintuitive behavior which has hurt us several times now:
db.c.insert({a: [1, {c: 1}]});
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db.c.insert({a: [1]});
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db.c.find({"a.b": {$exists: true}}) // Returns nothing.
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db.c.find({"a.b": {$ne: null}}) // Returns {a: [1]} !!!!
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That is, {$ne: null} doesn't necessarily return a subset of the things that {$exists: true} returns. This ticket is to track the work of changing the meaning of {$ne: null}.
- is duplicated by
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SERVER-42464 Find query fails with filter on field of a hash *in specified array element*
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- Closed
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- is related to
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- Open
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SERVER-36465 Non-multikey sparse indexes can be used to answer query with {$ne:null} predicate
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- Closed
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- related to
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- Closed
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