Installation
------------

Place the search_api_solr module either directly under the /modules directory
at the root of your Drupal installation, or place it under /modules/contrib
directory instead, to group all contributed modules together.

Next, you need to install the module's composer dependencies, there are
multiple ways to do this; you can read more in the documentation[1] on d.o.

You can now visit the /admin/modules page on your site and install the Solr
search module.

[1] https://www.drupal.org/documentation/install/composer-dependencies

Solr search
-----------

This module provides an implementation of the Search API which uses an Apache
Solr search server for indexing and searching. Before enabling or using this
module, you'll have to follow the instructions given in INSTALL.txt first.

The minimum support version for Search API Solr 8.x is Solr 4.5.1.
Any version below might work if you use your own Solr config.

For more detailed documentation, see the handbook [2].

[2] https://drupal.org/node/1999280

Running the test suite
----------------------

This module comes with a suite of automated tests. To execute those, you just
need to have a (correctly configured) Solr instance running at the following
address:
  http://localhost:8983/solr/d8
(This represents a core named "d8" in a default installation of Solr.)

Supported optional features
---------------------------

All Search API datatypes are supported by using appropriate Solr datatypes for
indexing them. By default, "String"/"URI" and "Integer"/"Duration" are defined
equivalently. However, through manual configuration of the used schema.xml this
can be changed arbitrarily. Using your own Solr extensions is thereby also
possible.

The "direct" parse mode for queries will result in the keys being directly used
as the query to Solr. For details about Lucene's query syntax, see [3]. There
are also some Solr additions to this, listed at [4]. Note however that, by
default, this module uses the dismax query handler, so searches like
"field:value" won't work with the "direct" mode.

[3] http://lucene.apache.org/java/2_9_1/queryparsersyntax.html
[4] http://wiki.apache.org/solr/SolrQuerySyntax

Regarding third-party features, the following are supported:

- search_api_autocomplete
  Introduced by module: search_api_autocomplete
  Lets you add autocompletion capabilities to search forms on the site. (See
  also "Hidden variables" below for Solr-specific customization.)
- search_api_facets
  Introduced by module: search_api_facetapi
  Allows you to create facetted searches for dynamically filtering search
  results.
- search_api_facets_operator_or
  Introduced by module: search_api_facetapi
  Allows the creation of OR facets.
- search_api_mlt
  Introduced by module: search_api_views
  Lets you display items that are similar to a given one. Use, e.g., to create
  a "More like this" block for node pages.
  NOTE: Due to a regression in Solr itself, "More like this" doesn't work with
  integer and float fields in Solr 4. As a work-around, you can index the fields
  (or copies of them) as string values. See [5] for details.
  Also, MLT with date fields isn't currently supported at all for any version.
- search_api_multi
  Introduced by module: search_api_multi
  Allows you to search multiple indexes at once, as long as they are on the same
  server. You can use this to let users simultaneously search all content on the
  site – nodes, comments, user profiles, etc.
- search_api_spellcheck
  Introduced by module: search_api_spellcheck
  Gives the option to display automatic spellchecking for searches.
- search_api_data_type_location
  Introduced by module: search_api_location
  Lets you index, filter and sort on location fields. Note, however, that only
  single-valued fields are currently supported for Solr 3.x, and that the option
  isn't supported at all in Solr 1.4.
- search_api_grouping
  Introduced by module: search_api_grouping [6]
  Lets you group search results based on indexed fields. For further information
  see the FieldCollapsing documentation in the solr wiki [7].

If you feel some service option is missing, or have other ideas for improving
this implementation, please file a feature request in the project's issue queue,
at [8].

[5] https://drupal.org/node/2004596
[6] https://drupal.org/sandbox/daspeter/1783280
[7] http://wiki.apache.org/solr/FieldCollapsing
[8] https://drupal.org/project/issues/search_api_solr

Specifics
---------

Please consider that, since Solr handles tokenizing, stemming and other
preprocessing tasks, activating any preprocessors in a search index' settings is
usually not needed or even cumbersome. If you are adding an index to a Solr
server you should therefore then disable all processors which handle such
classic preprocessing tasks. Enabling the HTML filter can be useful, though, as
the default config files included in this module don't handle stripping out HTML
tags.

Hidden variables
----------------

- search_api_solr.settings.autocomplete_max_occurrences (default: 0.9)
  By default, keywords that occur in more than 90% of results are ignored for
  autocomplete suggestions. This setting lets you modify that behaviour by
  providing your own ratio. Use 1 or greater to use all suggestions.
- search_api_solr.settings.index_prefix (default: '')
  By default, the index ID in the Solr server is the same as the index's machine
  name in Drupal. This setting will let you specify a prefix for the index IDs
  on this Drupal installation. Only use alphanumeric characters and underscores.
  Since changing the prefix makes the currently indexed data inaccessible, you
  should change this vairable only when no indexes are currently on any Solr
  servers.
- search_api_solr.settings.index_prefix_INDEX_ID (default: '')
  Same as above, but a per-index prefix. Use the index's machine name as
  INDEX_ID in the variable name. Per-index prefixing is done before the global
  prefix is added, so the global prefix will come first in the final name:
  (GLOBAL_PREFIX)(INDEX_PREFIX)(INDEX_ID)
  The same rules as above apply for setting the prefix.
- search_api_solr.settings.http_get_max_length (default: 4000)
  The maximum number of bytes that can be handled as an HTTP GET query when
  HTTP method is AUTO. Typically Solr can handle up to 65355 bytes, but Tomcat
  and Jetty will error at slightly less than 4096 bytes.
- search_api_solr.settings.cron_action (default: "spellcheck")
  The Search API Solr Search module can automatically execute some upkeep
  operations daily during cron runs. This variable determines what particular
  operation is carried out.
  - spellcheck: The "default" spellcheck dictionary used by Solr will be rebuilt
  so that spellchecking reflects the latest index state.
  - optimize: An "optimize" operation [9] is executed on the Solr server. As a
  result of this, all spellcheck dictionaries (that have "buildOnOptimize" set
  to "true") will be rebuilt, too.
  - none: No action is executed.
  If an unknown setting is encountered, it is interpreted as "none".
- search_api_solr.settings.site_hash (default: random)
  A unique hash specific to the local site, created the first time it is needed.
  Only change this if you want to display another server's results and you know
  what you are doing. Old indexed items will be lost when the hash is changed
  (without being automatically deleted from the Solr server!) and all items will
  have to be reindexed. Should only contain alphanumeric characters.

[9] http://wiki.apache.org/solr/UpdateXmlMessages#A.22commit.22_and_.22optimize.22

Customizing your Solr server
----------------------------

The schema.xml and solrconfig.xml files contain extensive comments on how to
add additional features or modify behaviour, e.g., for adding a language-
specific stemmer or a stopword list.
If you are interested in further customizing your Solr server to your needs,
see the Solr wiki at [10] for documentation. When editing the schema.xml and
solrconfig.xml files, please only edit the copies in the Solr configuration
directory, not directly the ones provided with this module.

[10] http://wiki.apache.org/solr/

You'll have to restart your Solr server after making such changes, for them to
take effect.

Developers
----------