```
CREATE TABLE a
(
    `number` UInt64,
    `x` MATERIALIZED x
)
ENGINE = MergeTree
ORDER BY number;
-- that should fail!

insert into a values (1);
Received exception from server (version 21.7.1):
Code: 47. DB::Exception: Received from localhost:9000. DB::Exception: Missing columns: 'x' while processing query: 'CAST(x, 'UInt8') AS x', required columns: 'x' 'x'. 
```
{
    auto it = columns.get<1>().find(column_name);
    return it != columns.get<1>().end() && it->default_desc.kind != ColumnDefaultKind::Alias;
}
bool ColumnsDescription::hasPhysicalOrSubcolumn(const String & column_name) const
{
    return hasPhysical(column_name) || subcolumns.find(column_name) != subcolumns.end();
}
static NamesAndTypesList getWithSubcolumns(NamesAndTypesList && source_list)
{
    NamesAndTypesList ret;
    for (const auto & col : source_list)
    {
        ret.emplace_back(col.name, col.type);
        for (const auto & subcolumn : col.type->getSubcolumnNames())
            ret.emplace_back(col.name, subcolumn, col.type, col.type->getSubcolumnType(subcolumn));
    }
    return ret;
}
NamesAndTypesList ColumnsDescription::getAllWithSubcolumns() const