outputMappings.put(symbol, new Input(channel, field));
field++;
}
projections.add(ProjectionFunctions.concat(packedProjections));
OperatorFactory operatorFactory = new FilterAndProjectOperatorFactory(context.getNextOperatorId(), FilterFunctions.TRUE_FUNCTION, projections.build());
return new PhysicalOperation(operatorFactory, outputMappings.build(), source);
}