final FieldIndex index = new FieldIndex( variableConstraint.getFieldExtractor(),
variableConstraint.getRequiredDeclarations()[0],
variableConstraint.getEvaluator() );
LeftTupleMemory tupleMemory;
if ( this.conf.isIndexLeftBetaMemory() ) {
tupleMemory = new LeftTupleIndexHashTable( new FieldIndex[]{index} );
} else {
tupleMemory = new LeftTupleList();
}
RightTupleMemory factHandleMemory;