[[analysis-multiplexer-tokenfilter]]
=== Multiplexer token filter
++++
<titleabbrev>Multiplexer</titleabbrev>
++++

A token filter of type `multiplexer` will emit multiple tokens at the same position,
each version of the token having been run through a different filter.  Identical
output tokens at the same position will be removed.

WARNING: If the incoming token stream has duplicate tokens, then these will also be
removed by the multiplexer

[discrete]
=== Options
[horizontal]
filters:: a list of token filters to apply to incoming tokens.  These can be any
  token filters defined elsewhere in the index mappings.  Filters can be chained
  using a comma-delimited string, so for example `"lowercase, porter_stem"` would
  apply the `lowercase` filter and then the `porter_stem` filter to a single token.

WARNING: <<analysis-shingle-tokenfilter,Shingle>> or multi-word synonym token filters will not function normally
  when they are declared in the filters array because they read ahead internally
  which is unsupported by the multiplexer

preserve_original:: if `true` (the default) then emit the original token in
  addition to the filtered tokens


[discrete]
=== Settings example

You can set it up like:

[source,console]
--------------------------------------------------
PUT /multiplexer_example
{
  "settings": {
    "analysis": {
      "analyzer": {
        "my_analyzer": {
          "tokenizer": "standard",
          "filter": [ "my_multiplexer" ]
        }
      },
      "filter": {
        "my_multiplexer": {
          "type": "multiplexer",
          "filters": [ "lowercase", "lowercase, porter_stem" ]
        }
      }
    }
  }
}
--------------------------------------------------

And test it like:

[source,console]
--------------------------------------------------
POST /multiplexer_example/_analyze
{
  "analyzer" : "my_analyzer",
  "text" : "Going HOME"
}
--------------------------------------------------
// TEST[continued]

And it'd respond:

[source,console-result]
--------------------------------------------------
{
  "tokens": [
    {
      "token": "Going",
      "start_offset": 0,
      "end_offset": 5,
      "type": "<ALPHANUM>",
      "position": 0
    },
    {
      "token": "going",
      "start_offset": 0,
      "end_offset": 5,
      "type": "<ALPHANUM>",
      "position": 0
    },
    {
      "token": "go",
      "start_offset": 0,
      "end_offset": 5,
      "type": "<ALPHANUM>",
      "position": 0
    },
    {
      "token": "HOME",
      "start_offset": 6,
      "end_offset": 10,
      "type": "<ALPHANUM>",
      "position": 1
    },
    {
      "token": "home",          <1>
      "start_offset": 6,
      "end_offset": 10,
      "type": "<ALPHANUM>",
      "position": 1
    }
  ]
}
--------------------------------------------------

<1> The stemmer has also emitted a token `home` at position 1, but because it is a
duplicate of this token it has been removed from the token stream

NOTE: The synonym and synonym_graph filters use their preceding analysis chain to
parse and analyse their synonym lists, and will throw an exception if that chain
contains token filters that produce multiple tokens at the same position.
If you want to apply synonyms to a token stream containing a multiplexer, then you
should append the synonym filter to each relevant multiplexer filter list, rather than
placing it after the multiplexer in the main token chain definition.
