
```
select *
from (
select 'table' as table, toInt64(10) as rows, toInt64(101) as elements
union all
select 'another table' as table, toInt64(0) as rows, toInt64(0) as elements
)
where rows - elements <> 0

DB::Exception: Block structure mismatch in Pipe::unitePipes stream: different number of columns:
table String String(size = 0), rows Int64 Int64(size = 0), elements Int64 Int64(size = 0)
table String String(size = 0), rows Int64 Int64(size = 0), elements Int64 Int64(size = 0), dummy UInt8 UInt8(size = 0) (version 21.5.3.1 (official build))
```
Node node;
                node.type = ActionType::COLUMN;
                node.result_name = predicate->result_type->getName();
                node.column = DataTypeString().createColumnConst(0, node.result_name);
                node.result_type = std::make_shared<DataTypeString>();
                const auto * right_arg = &nodes.emplace_back(std::move(node));
                const auto * left_arg = new_children.front();
                predicate->children = {left_arg, right_arg};
                auto arguments = prepareFunctionArguments(predicate->children);
                FunctionOverloadResolverPtr func_builder_cast = CastOverloadResolver<CastType::nonAccurate>::createImpl(false);
                predicate->function_builder = func_builder_cast;
                predicate->function_base = predicate->function_builder->build(arguments);
                predicate->function = predicate->function_base->prepare(arguments);
            }
        }
        else
        {
            
            
            predicate->children.swap(new_children);
            auto arguments = prepareFunctionArguments(predicate->children);
            predicate->function_base = predicate->function_builder->build(arguments);
            predicate->function = predicate->function_base->prepare(arguments);
        }
        removeUnusedActions(false);
    }
    return actions;
}
}