[[analysis-pathhierarchy-tokenizer]]
=== Path hierarchy tokenizer
++++
<titleabbrev>Path hierarchy</titleabbrev>
++++

The `path_hierarchy` tokenizer takes a hierarchical value like a filesystem
path, splits on the path separator, and emits a term for each component in the
tree.

[discrete]
=== Example output

[source,console]
---------------------------
POST _analyze
{
  "tokenizer": "path_hierarchy",
  "text": "/one/two/three"
}
---------------------------

/////////////////////

[source,console-result]
----------------------------
{
  "tokens": [
    {
      "token": "/one",
      "start_offset": 0,
      "end_offset": 4,
      "type": "word",
      "position": 0
    },
    {
      "token": "/one/two",
      "start_offset": 0,
      "end_offset": 8,
      "type": "word",
      "position": 0
    },
    {
      "token": "/one/two/three",
      "start_offset": 0,
      "end_offset": 14,
      "type": "word",
      "position": 0
    }
  ]
}
----------------------------

/////////////////////



The above text would produce the following terms:

[source,text]
---------------------------
[ /one, /one/two, /one/two/three ]
---------------------------

[discrete]
=== Configuration

The `path_hierarchy` tokenizer accepts the following parameters:

[horizontal]
`delimiter`::
    The character to use as the path separator. Defaults to `/`.

`replacement`::
    An optional replacement character to use for the delimiter.
    Defaults to the `delimiter`.

`buffer_size`::
    The number of characters read into the term buffer in a single pass.
    Defaults to `1024`. The term buffer will grow by this size until all the
    text has been consumed. It is advisable not to change this setting.

`reverse`::
    If set to `true`, emits the tokens in reverse order. Defaults to `false`.

`skip`::
    The number of initial tokens to skip. Defaults to `0`.

[discrete]
=== Example configuration

In this example, we configure the `path_hierarchy` tokenizer to split on `-`
characters, and to replace them with `/`. The first two tokens are skipped:

[source,console]
----------------------------
PUT my-index-000001
{
  "settings": {
    "analysis": {
      "analyzer": {
        "my_analyzer": {
          "tokenizer": "my_tokenizer"
        }
      },
      "tokenizer": {
        "my_tokenizer": {
          "type": "path_hierarchy",
          "delimiter": "-",
          "replacement": "/",
          "skip": 2
        }
      }
    }
  }
}

POST my-index-000001/_analyze
{
  "analyzer": "my_analyzer",
  "text": "one-two-three-four-five"
}
----------------------------

/////////////////////

[source,console-result]
----------------------------
{
  "tokens": [
    {
      "token": "/three",
      "start_offset": 7,
      "end_offset": 13,
      "type": "word",
      "position": 0
    },
    {
      "token": "/three/four",
      "start_offset": 7,
      "end_offset": 18,
      "type": "word",
      "position": 0
    },
    {
      "token": "/three/four/five",
      "start_offset": 7,
      "end_offset": 23,
      "type": "word",
      "position": 0
    }
  ]
}
----------------------------

/////////////////////


The above example produces the following terms:

[source,text]
---------------------------
[ /three, /three/four, /three/four/five ]
---------------------------

If we were to set `reverse` to `true`, it would produce the following:

[source,text]
---------------------------
[ one/two/three/, two/three/, three/ ]
---------------------------

[discrete]
[[analysis-pathhierarchy-tokenizer-detailed-examples]]
=== Detailed examples

A common use-case for the `path_hierarchy` tokenizer is filtering results by 
file paths. If indexing a file path along with the data, the use of the 
`path_hierarchy` tokenizer to analyze the path allows filtering the results 
by different parts of the file path string.


This example configures an index to have two custom analyzers and applies
those analyzers to multifields of the `file_path` text field that will 
store filenames. One of the two analyzers uses reverse tokenization.
Some sample documents are then indexed to represent some file paths
for photos inside photo folders of two different users.


[source,console]
--------------------------------------------------
PUT file-path-test
{
  "settings": {
    "analysis": {
      "analyzer": {
        "custom_path_tree": {
          "tokenizer": "custom_hierarchy"
        },
        "custom_path_tree_reversed": {
          "tokenizer": "custom_hierarchy_reversed"
        }
      },
      "tokenizer": {
        "custom_hierarchy": {
          "type": "path_hierarchy",
          "delimiter": "/"
        },
        "custom_hierarchy_reversed": {
          "type": "path_hierarchy",
          "delimiter": "/",
          "reverse": "true"
        }
      }
    }
  },
  "mappings": {
    "properties": {
      "file_path": {
        "type": "text",
        "fields": {
          "tree": {
            "type": "text",
            "analyzer": "custom_path_tree"
          },
          "tree_reversed": {
            "type": "text",
            "analyzer": "custom_path_tree_reversed"
          }
        }
      }
    }
  }
}

POST file-path-test/_doc/1
{
  "file_path": "/User/alice/photos/2017/05/16/my_photo1.jpg"
}

POST file-path-test/_doc/2
{
  "file_path": "/User/alice/photos/2017/05/16/my_photo2.jpg"
}

POST file-path-test/_doc/3
{
  "file_path": "/User/alice/photos/2017/05/16/my_photo3.jpg"
}

POST file-path-test/_doc/4
{
  "file_path": "/User/alice/photos/2017/05/15/my_photo1.jpg"
}

POST file-path-test/_doc/5
{
  "file_path": "/User/bob/photos/2017/05/16/my_photo1.jpg"
}
--------------------------------------------------


A search for a particular file path string against the text field matches all 
the example documents, with Bob's documents ranking highest due to `bob` also 
being one of the terms created by the standard analyzer boosting relevance for
Bob's documents.

[source,console]
--------------------------------------------------
GET file-path-test/_search
{
  "query": {
    "match": {
      "file_path": "/User/bob/photos/2017/05"
    }
  }
}
--------------------------------------------------
// TEST[continued]

It's simple to match or filter documents with file paths that exist within a
particular directory using the `file_path.tree` field.

[source,console]
--------------------------------------------------
GET file-path-test/_search
{
  "query": {
    "term": {
      "file_path.tree": "/User/alice/photos/2017/05/16"
    }
  }
}
--------------------------------------------------
// TEST[continued]

With the reverse parameter for this tokenizer, it's also possible to match
from the other end of the file path, such as individual file names or a deep
level subdirectory. The following example shows a search for all files named
`my_photo1.jpg` within any directory via the `file_path.tree_reversed` field 
configured to use the reverse parameter in the mapping.


[source,console]
--------------------------------------------------
GET file-path-test/_search
{
  "query": {
    "term": {
      "file_path.tree_reversed": {
        "value": "my_photo1.jpg"
      }
    }
  }
}
--------------------------------------------------
// TEST[continued]

Viewing the tokens generated with both forward and reverse is instructive
in showing the tokens created for the same file path value.


[source,console]
--------------------------------------------------
POST file-path-test/_analyze
{
  "analyzer": "custom_path_tree",
  "text": "/User/alice/photos/2017/05/16/my_photo1.jpg"
}

POST file-path-test/_analyze
{
  "analyzer": "custom_path_tree_reversed",
  "text": "/User/alice/photos/2017/05/16/my_photo1.jpg"
}
--------------------------------------------------
// TEST[continued]


It's also useful to be able to filter with file paths when combined with other
types of searches, such as this example looking for any files paths with `16` 
that also must be in Alice's photo directory.

[source,console]
--------------------------------------------------
GET file-path-test/_search
{
  "query": {
    "bool" : {
      "must" : {
        "match" : { "file_path" : "16" }
      },
      "filter": {
        "term" : { "file_path.tree" : "/User/alice" }
      }
    }
  }
}
--------------------------------------------------
// TEST[continued]
