sqlalchemy.sql.schema.Index

A table-level INDEX. Defines a composite (one or more column) INDEX. E.g.:: sometable = Table("sometable", metadata, Column("name", String(50)), Column("address", String(100)) ) Index("some_index", sometable.c.name) For a no-frills, single column index, adding :class:`_schema.Column` also supports ``index=True``:: sometable = Table("sometable", metadata, Column("name", String(50), index=True) ) For a composite index, multiple columns can be specified:: Index("some_index", sometable.c.name, sometable.c.address) Functional indexes are supported as well, typically by using the :data:`.func` construct in conjunction with table-bound :class:`_schema.Column` objects:: Index("some_index", func.lower(sometable.c.name)) An :class:`.Index` can also be manually associated with a :class:`_schema.Table`, either through inline declaration or using :meth:`_schema.Table.append_constraint`. When this approach is used, the names of the indexed columns can be specified as strings:: Table("sometable", metadata, Column("name", String(50)), Column("address", String(100)), Index("some_index", "name", "address") ) To support functional or expression-based indexes in this form, the :func:`_expression.text` construct may be used:: from sqlalchemy import text Table("sometable", metadata, Column("name", String(50)), Column("address", String(100)), Index("some_index", text("lower(name)")) ) .. versionadded:: 0.9.5 the :func:`_expression.text` construct may be used to specify :class:`.Index` expressions, provided the :class:`.Index` is explicitly associated with the :class:`_schema.Table`. .. seealso:: :ref:`schema_indexes` - General information on :class:`.Index`. :ref:`postgresql_indexes` - PostgreSQL-specific options available for the :class:`.Index` construct. :ref:`mysql_indexes` - MySQL-specific options available for the :class:`.Index` construct. :ref:`mssql_indexes` - MSSQL-specific options available for the :class:`.Index` construct.