{
    "_yql_row_spec"={
        "Type"=["StructType";[
            ["key"; ["DataType"; "String"]];
            ["subkey"; ["DataType"; "String"]];
            ["value"; ["DataType"; "String"]];
        ]];
        "SortMembers"=["key"; "subkey"];
        "SortedBy"=["key"; "subkey"];
        "SortDirections"=[1; 1];
        "SortedByTypes"=[["DataType";"String"]; ["DataType";"String"]]
    };
    "_yql_dynamic"=%true;
    "schema"=<
        "strict" = %true;
        "unique_keys" = %true
    >[
        {
            "name" = "key";
            "type" = "string";
            "sort_order" = "ascending";
        };
        {
            "name" = "subkey";
            "type" = "string";
            "sort_order" = "ascending";
        };
        {
            "name" = "value";
            "type" = "string";
        };
    ]
}