Support dotted field past positional operator with positional operator projection

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    • Type: Improvement
    • Resolution: Unresolved
    • Priority: Major - P3
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    • Affects Version/s: None
    • Component/s: Querying
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    • Query Optimization
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      With update the positional operator can be combined with additional fields after the dollar sign, for example 'a.$.b' to indicate the 'b' field within the matched array element. This is not yet supported with positional projections.

      Observed behavior: Projecting

      { 'a.$.b':1 }

      is equivalent to projecting

      { 'a.$':1 }

      .
      Expected behavior: Projecting

      { 'a.$.b':1 }

      will project only the 'b' field within the matching array element.

      Test

      c = db.c;
c.drop();

c.save( { a:[ { b:10, c:1 }, { b:5, c:1 } ] } );

// Update the 'b' field within the matching array element.
c.update( { 'a.b':5 }, { $set:{ 'a.$.b':6 } } );
printjson( c.findOne() );

// Projects the entire matching array element.
printjson( c.find( { 'a.b':6 }, { 'a.$':1 } ).toArray() );

// Projects the entire matching array element (contrary to expected behavior).
printjson( c.find( { 'a.b':6 }, { 'a.$.b':1 } ).toArray() );

// Projects the 'b' fields within all array elements.
printjson( c.find( { 'a.b':6 }, { 'a.b':1 } ).toArray() );

            Assignee:
            [DO NOT USE] Backlog - Query Optimization
            Reporter:
            Aaron Staple (Inactive)
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            0 Vote for this issue
            Watchers:
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              Created:
              Updated: