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  1. Core Server
  2. SERVER-8152

aggregation array sort differs from query/index array sort; causes aggregation results to change depending on sort optimizations

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    • Type: Icon: Bug Bug
    • Resolution: Duplicate
    • Priority: Icon: Major - P3 Major - P3
    • None
    • Affects Version/s: None
    • Component/s: Aggregation Framework
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    • Query
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      c = db.c;
c.drop();

c.save( { _id:'x', a:[ 2, 1 ] } );
c.save( { _id:'y', a:[ 1, 2 ] } );

// no index                                                                                    
printjson( c.aggregate( { $sort:{ a:1 } } ) );

// with index                                                                                  
c.ensureIndex( { a:1 } );
printjson( c.aggregate( { $sort:{ a:1 } } ) );
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      c = db.c; c.drop(); c.save( { _id: 'x' , a:[ 2, 1 ] } ); c.save( { _id: 'y' , a:[ 1, 2 ] } ); // no index printjson( c.aggregate( { $sort:{ a:1 } } ) ); // with index c.ensureIndex( { a:1 } ); printjson( c.aggregate( { $sort:{ a:1 } } ) );

      Aggregation and queries/indexing sort arrays differently. This can cause the results returned by an aggregation to change when a sort stage is removed in favor of using an index.

            Assignee:
            backlog-server-query Backlog - Query Team (Inactive)
            Reporter:
            aaron Aaron Staple
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              Created:
              Updated:
              Resolved: