Method _create_select_clause

tests/comparison/query_generator.py:268–373

(self,
      table_exprs,
      select_item_data_types,
      required_select_item_type,
      require_aggregate)

    return WithClause(with_clause_inline_views)

  def _create_select_clause(self,
      table_exprs,
      select_item_data_types,
      required_select_item_type,
      require_aggregate):
    if select_item_data_types:
      select_item_data_types = tuple(select_item_data_types)
    if select_item_data_types \
        and required_select_item_type \
        and not issubclass(required_select_item_type, select_item_data_types):
      raise Exception('Required select item type is not in allowed types')

    # Generate column types for the select clause if not specified.
    if not select_item_data_types:
      select_item_data_types = []
      desired_item_count = self.profile.get_select_item_count()
      if required_select_item_type:
        select_item_data_types.append(required_select_item_type)
      while len(select_item_data_types) < desired_item_count:
        select_item_data_types.append(self.profile.choose_type(table_exprs.col_types))
      shuffle(select_item_data_types)
      select_item_data_types = tuple(select_item_data_types)

    # We want to assign BASIC, AGG or ANALYTIC to each column. We want to prevent GROUP BY
    # float_col, because the groupings will differ across databases because floats are
    # approximate values.
    column_categories = ['-' for _ in select_item_data_types]
    if require_aggregate:
      column_categories[randint(0, len(column_categories) - 1)] = 'AGG'
    # Assign AGG and ANALYTIC some columns
    for i in range(len(column_categories)):
      item_category = self.profile._choose_from_weights(
          self.profile.weights('SELECT_ITEM_CATEGORY'))
      if item_category in ('AGG', 'ANALYTIC'):
        column_categories[i] = item_category
    agg_present = 'AGG' in column_categories
    # Assign BASIC to the remaining columns
    for i in range(len(column_categories)):
      if column_categories[i] == '-':
        if select_item_data_types[i].is_approximate() and agg_present:
          column_categories[i] = 'AGG'
        else:
          # If AGG column is present, BASIC can only be assigned to a column if it's not a
          # Float.
          column_categories[i] = 'BASIC'

    select_items = []

    for i, column_category in enumerate(column_categories):
      if column_category == 'BASIC':
        select_items.append(self._create_basic_select_item(
          table_exprs, select_item_data_types[i]))
      else:
        select_items.append((column_category, select_item_data_types[i]))

    analytic_count = sum(1 for c in column_category if c == 'ANALYTIC')

    select_item_exprs = \