[[analysis-analyzers]]
== Analyzers

Analyzers are composed of a single <<analysis-tokenizers,Tokenizer>> 
and zero or more <<analysis-tokenfilters,TokenFilters>>. The tokenizer may 
be preceded by one or more <<analysis-charfilters,CharFilters>>.
The analysis module allows you to register `Analyzers` under logical
names which can then be referenced either in mapping definitions or in
certain APIs. 

Elasticsearch comes with a number of prebuilt analyzers which are
ready to use.  Alternatively, you can combine the built in
character filters, tokenizers and token filters to create 
<<analysis-custom-analyzer,custom analyzers>>.

[float]
=== Default Analyzers

An analyzer is registered under a logical name. It can then be
referenced from mapping definitions or certain APIs. When none are
defined, defaults are used. There is an option to define which analyzers
will be used by default when none can be derived.

The `default` logical name allows one to configure an analyzer that will
be used both for indexing and for searching APIs. The `default_index`
logical name can be used to configure a default analyzer that will be
used just when indexing, and the `default_search` can be used to
configure a default analyzer that will be used just when searching.

[float]
=== Aliasing Analyzers

Analyzers can be aliased to have several registered lookup names
associated with them. For example, the following will allow 
the `standard` analyzer to also be referenced with `alias1`
and `alias2` values.


[source,js]
--------------------------------------------------
index :
  analysis :
    analyzer :
      standard :
        alias: [alias1, alias2]
        type : standard
        stopwords : [test1, test2, test3]
--------------------------------------------------

Below is a list of the built in analyzers.

include::analyzers/standard-analyzer.asciidoc[]

include::analyzers/simple-analyzer.asciidoc[]

include::analyzers/whitespace-analyzer.asciidoc[]

include::analyzers/stop-analyzer.asciidoc[]

include::analyzers/keyword-analyzer.asciidoc[]

include::analyzers/pattern-analyzer.asciidoc[]

include::analyzers/lang-analyzer.asciidoc[]

include::analyzers/snowball-analyzer.asciidoc[]

include::analyzers/custom-analyzer.asciidoc[]