{
    "_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";
        };
    ]
}