{"_yql_row_spec"={
    "Type"=["StructType";[
        ["key";["DataType";"String"]];
        ["subkey";["OptionalType"; ["DataType";"String";]]];
        ["value";["DataType";"String"]]
    ]];
    "SortDirections"=[1;1;];
    "SortedBy"=["key";"subkey";];
    "SortedByTypes"=[["DataType";"String";];["OptionalType"; ["DataType";"String";]];];
    "SortMembers"=["key";"subkey";];
}}