message: Display the first partition.
diff: @@ -329,7 +329,7 @@ class PrestoEngineSpec(BaseEngineSpec):
  full_table_name = "{}.{}".format(schema_name, table_name)
  pql = cls._partition_query(full_table_name)
  col_name, latest_part = cls.latest_partition(
  - table_name, schema_name, database)
  + table_name, schema_name, database, show_first=True)
  return {
  'partitions': {
  'cols': cols,
  @@ -423,7 +423,7 @@ class PrestoEngineSpec(BaseEngineSpec):
  return df.to_records(index=False)[0][0]
  @classmethod
  - def latest_partition(cls, table_name, schema, database):
  + def latest_partition(cls, table_name, schema, database, show_first=False):
  """Returns col name and the latest (max) partition value for a table
  :param table_name: the name of the table
  @@ -432,6 +432,9 @@ class PrestoEngineSpec(BaseEngineSpec):
  :type schema: str
  :param database: database query will be run against
  :type database: models.Database
  + :param show_first: displays the value for the first partitioning key
  + if there are many partitioning keys
  + :type show_first: bool
  >>> latest_partition('foo_table')
  '2018-01-01'
  @@ -440,7 +443,7 @@ class PrestoEngineSpec(BaseEngineSpec):
  if len(indexes[0]['column_names']) < 1:
  raise SupersetTemplateException(
  "The table should have one partitioned field")
  - elif len(indexes[0]['column_names']) > 1:
  + elif not show_first and len(indexes[0]['column_names']) > 1:
  raise SupersetTemplateException(
  "The table should have a single partitioned field "
  "to use this function. You may want to use "
  