text: from django.core import checks
  from django.db.backends.base.validation import BaseDatabaseValidation
  
  
  class DatabaseValidation(BaseDatabaseValidation):
      def check_field_type(self, field, field_type):
          """Oracle doesn't support a database index on some data types."""
          errors = []
          if field.db_index and field_type.lower() in self.connection._limited_data_types:
              errors.append(
                  checks.Warning(
                      "Oracle does not support a database index on %s columns."
                      % field_type,
                      hint=(
                          "An index won't be created. Silence this warning if "
                          "you don't care about it."
                      ),
                      obj=field,
                      id="fields.W162",
                  )
              )
          return errors
  