string constants prevent optimization of non string sensitive operators

XMLWordPrintableJSON

    • Type: Improvement
    • Resolution: Done
    • Priority: Major - P3
    • 2.5.3
    • Affects Version/s: None
    • Component/s: Aggregation Framework
    • None
    • None
    • None
    • None
    • None
    • None
    • None
    • None

      Observed behavior: The presence of a string in a $and/$or expression prevents optimization.
      Expected behavior: Optimizations will be applied in spite of the string expressions.

              /*
          If there are any strings, we can't re-arrange anything, so stop
          now.

          LATER:  we could concatenate adjacent strings as a special case.
         */
        if (stringCount)
            return intrusive_ptr<Expression>(this);

      Test:

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

c.save( { x:true } );

// Optimized to 'false'.
printjson( c.runCommand( 'aggregate', { pipeline:[ { $project:{ a:{ $and:[ 0, 1, '$x' ] \
} } } ], explain:true } ) );
// Not optimized.
printjson( c.runCommand( 'aggregate', { pipeline:[ { $project:{ a:{ $and:[ 0, 1, '', '$x\
' ] } } } ], explain:true } ) );

            Assignee:
            David Storch
            Reporter:
            Aaron Staple (Inactive)
            Votes:
            0 Vote for this issue
            Watchers:
            2 Start watching this issue

              Created:
              Updated:
              Resolved: