Details
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Improvement
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Status: Backlog
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Major - P3
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Resolution: Unresolved
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None
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None
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None
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Query Optimization
Description
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
will project only the 'b' field within the matching array element.
Test
c = db.c;
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c.drop();
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c.save( { a:[ { b:10, c:1 }, { b:5, c:1 } ] } );
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// Update the 'b' field within the matching array element.
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c.update( { 'a.b':5 }, { $set:{ 'a.$.b':6 } } );
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printjson( c.findOne() );
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// Projects the entire matching array element.
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printjson( c.find( { 'a.b':6 }, { 'a.$':1 } ).toArray() );
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// Projects the entire matching array element (contrary to expected behavior).
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printjson( c.find( { 'a.b':6 }, { 'a.$.b':1 } ).toArray() );
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// Projects the 'b' fields within all array elements.
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printjson( c.find( { 'a.b':6 }, { 'a.b':1 } ).toArray() );
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Attachments
Issue Links
- is related to
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SERVER-6864 positional operator projection inclusion can mess up array based non positional operator
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- Closed
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SERVER-43334 Disallow additional path components after the positional projection ("$") operator
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- Closed
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