class MyPostgresPersistence(IdentifiableJsonPostgresPersistence):

    def __init__(self):
        super(MyPostgresPersistence, self).__init__('mydata_json2')

    def _define_schema(self):
        # clear all previously autogenerated schemas
        self._clear_schema()
        # create a table 
        self._ensure_table()
        # create an index
        self._ensure_index(self._table_name + '_json_key', {"(data->>'key')": 1}, {'unique': None})

    def get_one_random(self, correlation_id: Optional[str], filter: Any) -> MyData:
        return super().get_one_random(correlation_id, filter)

    def get_list_by_filter(self, correlation_id: Optional[str], filter: Any, sort: Any, select: Any) -> List[MyData]:
        return super().get_list_by_filter(correlation_id, filter, sort, select)

    def get_count_by_filter(self, correlation_id: Optional[str], filter: Any) -> int:
        return super().get_count_by_filter(correlation_id, filter)

    def get_page_by_filter(self, correlation_id: Optional[str], filter: Any, paging: PagingParams, sort: Any, select: Any) -> DataPage: 
        return super().get_page_by_filter(correlation_id, filter, paging, sort, select)

    def delete_by_filter(self, correlation_id: Optional[str], filter: Any) -> int:
        return super().delete_by_filter(correlation_id, filter)