
```
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))
```
{
    for (const auto & node : nodes)
        if (node.type == ActionType::ARRAY_JOIN)
            return true;
    return false;
}
bool ActionsDAG::hasStatefulFunctions() const
{
    for (const auto & node : nodes)
        if (node.type == ActionType::FUNCTION && node.function_base->isStateful())
            return true;
    return false;
}
bool ActionsDAG::trivial() const
{
    for (const auto & node : nodes)
        if (node.type == ActionType::FUNCTION || node.type == ActionType::ARRAY_JOIN)
            return false;
    return true;
}
void ActionsDAG::addMaterializingOutputActions()