
```
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::ALIAS;
    node.result_type = child.result_type;
    node.result_name = std::move(alias);
    node.column = child.column;
    node.children.emplace_back(&child);
    return addNode(std::move(node));
}
const ActionsDAG::Node & ActionsDAG::addArrayJoin(const Node & child, std::string result_name)
{
    const DataTypeArray * array_type = typeid_cast<const DataTypeArray *>(child.result_type.get());
    if (!array_type)
        throw Exception("ARRAY JOIN requires array argument", ErrorCodes::TYPE_MISMATCH);
    Node node;
    node.type = ActionType::ARRAY_JOIN;
    node.result_type = array_type->getNestedType();
    node.result_name = std::move(result_name);
    node.children.emplace_back(&child);
    return addNode(std::move(node));
}
const ActionsDAG::Node & ActionsDAG::addFunction(