operations.py 文件源码

def drop_index(self, name, table_name=None, schema=None):
        """Issue a "drop index" instruction using the current
        migration context.

        e.g.::

            drop_index("accounts")

        :param name: name of the index.
        :param table_name: name of the owning table.  Some
         backends such as Microsoft SQL Server require this.
        :param schema: Optional schema name to operate within.  To control
         quoting of the schema outside of the default behavior, use
         the SQLAlchemy construct
         :class:`~sqlalchemy.sql.elements.quoted_name`.

         .. versionadded:: 0.7.0 'schema' can now accept a
            :class:`~sqlalchemy.sql.elements.quoted_name` construct.

        """
        # need a dummy column name here since SQLAlchemy
        # 0.7.6 and further raises on Index with no columns
        self.impl.drop_index(
            self._index(name, table_name, ['x'], schema=schema)
        )