.. _wagtailsearch_backends:

========
Backends
========

Wagtailsearch has support for multiple backends giving you the choice between using the database for search or an external service such as Elasticsearch.

You can configure which backend to use with the ``WAGTAILSEARCH_BACKENDS`` setting:

.. code-block:: python

  WAGTAILSEARCH_BACKENDS = {
      'default': {
          'BACKEND': 'wagtail.wagtailsearch.backends.db.DBSearch',
      }
  }


``AUTO_UPDATE``
===============

By default, Wagtail will automatically keep all indexes up to date. This could impact performance when editing content, especially if your index is hosted on an external service.

The ``AUTO_UPDATE`` setting allows you to disable this on a per-index basis:

.. code-block:: python

  WAGTAILSEARCH_BACKENDS = {
      'default': {
          'BACKEND': ...,
          'AUTO_UPDATE': False,
      }
  }

If you have disabled auto update, you must run the :ref:`update_index` command on a regular basis to keep the index in sync with the database.


``BACKEND``
===========

Here's a list of backends that Wagtail supports out of the box.

.. _wagtailsearch_backends_database:

Database Backend (default)
--------------------------

``wagtail.wagtailsearch.backends.db.DBSearch``

The database backend is very basic and is intended only to be used in development and on small sites. It cannot order results by relevance making it not very useful when searching a large amount of pages.

It also doesn't support:

 - Searching on fields in subclasses of ``Page`` (unless the class is being searched directly)
 - :ref:`wagtailsearch_indexing_callable_fields`
 - Converting accented characters to ASCII

If any of these features are important to you, we recommend using Elasticsearch instead.


Elasticsearch Backend
---------------------

``wagtail.wagtailsearch.backends.elasticsearch.ElasticSearch``

Prerequisites are the `Elasticsearch`_ service itself and, via pip, the `elasticsearch-py`_ package:

.. _Elasticsearch: https://www.elastic.co/products/elasticsearch


.. code-block:: guess

  pip install elasticsearch

The backend is configured in settings:

.. code-block:: python

  WAGTAILSEARCH_BACKENDS = {
      'default': {
          'BACKEND': 'wagtail.wagtailsearch.backends.elasticsearch.ElasticSearch',
          'URLS': ['http://localhost:9200'],
          'INDEX': 'wagtail',
          'TIMEOUT': 5,
      }
  }

Other than ``BACKEND`` the keys are optional and default to the values shown. In addition, any other keys are passed directly to the Elasticsearch constructor as case-sensitive keyword arguments (e.g. ``'max_retries': 1``).

If you prefer not to run an Elasticsearch server in development or production, there are many hosted services available, including `Searchly`_, who offer a free account suitable for testing and development. To use Searchly:

-  Sign up for an account at `dashboard.searchly.com/users/sign\_up`_
-  Use your Searchly dashboard to create a new index, e.g. 'wagtaildemo'
-  Note the connection URL from your Searchly dashboard
-  Configure ``URLS`` and ``INDEX`` in the Elasticsearch entry in ``WAGTAILSEARCH_BACKENDS``
-  Run ``./manage.py update_index``

.. _elasticsearch-py: http://elasticsearch-py.readthedocs.org
.. _Searchly: http://www.searchly.com/
.. _dashboard.searchly.com/users/sign\_up: https://dashboard.searchly.com/users/sign_up


Rolling Your Own
----------------

Wagtail search backends implement the interface defined in ``wagtail/wagtail/wagtailsearch/backends/base.py``. At a minimum, the backend's ``search()`` method must return a collection of objects or ``model.objects.none()``. For a fully-featured search backend, examine the Elasticsearch backend code in ``elasticsearch.py``.