Path hierarchy tokenizer
editPath hierarchy tokenizer
editThe 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. The path_hierarcy
tokenizer uses Lucene’s
PathHierarchyTokenizer
underneath.
Example output
editresponse = client.indices.analyze( body: { tokenizer: 'path_hierarchy', text: '/one/two/three' } ) puts response
POST _analyze { "tokenizer": "path_hierarchy", "text": "/one/two/three" }
The above text would produce the following terms:
[ /one, /one/two, /one/two/three ]
Configuration
editThe path_hierarchy
tokenizer accepts the following parameters:
|
The character to use as the path separator. Defaults to |
|
An optional replacement character to use for the delimiter.
Defaults to the |
|
The number of characters read into the term buffer in a single pass.
Defaults to |
|
If |
|
The number of initial tokens to skip. Defaults to |
Example configuration
editIn this example, we configure the path_hierarchy
tokenizer to split on -
characters, and to replace them with /
. The first two tokens are skipped:
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" }
The above example produces the following terms:
[ /three, /three/four, /three/four/five ]
If we were to set reverse
to true
, it would produce the following:
[ one/two/three/, two/three/, three/ ]
Detailed examples
editA 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.
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.
response = client.search( index: 'file-path-test', body: { query: { match: { file_path: '/User/bob/photos/2017/05' } } } ) puts response
GET file-path-test/_search { "query": { "match": { "file_path": "/User/bob/photos/2017/05" } } }
It’s simple to match or filter documents with file paths that exist within a
particular directory using the file_path.tree
field.
response = client.search( index: 'file-path-test', body: { query: { term: { "file_path.tree": '/User/alice/photos/2017/05/16' } } } ) puts response
GET file-path-test/_search { "query": { "term": { "file_path.tree": "/User/alice/photos/2017/05/16" } } }
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.
response = client.search( index: 'file-path-test', body: { query: { term: { "file_path.tree_reversed": { value: 'my_photo1.jpg' } } } } ) puts response
GET file-path-test/_search { "query": { "term": { "file_path.tree_reversed": { "value": "my_photo1.jpg" } } } }
Viewing the tokens generated with both forward and reverse is instructive in showing the tokens created for the same file path value.
response = client.indices.analyze( index: 'file-path-test', body: { analyzer: 'custom_path_tree', text: '/User/alice/photos/2017/05/16/my_photo1.jpg' } ) puts response response = client.indices.analyze( index: 'file-path-test', body: { analyzer: 'custom_path_tree_reversed', text: '/User/alice/photos/2017/05/16/my_photo1.jpg' } ) puts response
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" }
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.
response = client.search( index: 'file-path-test', body: { query: { bool: { must: { match: { file_path: '16' } }, filter: { term: { "file_path.tree": '/User/alice' } } } } } ) puts response
GET file-path-test/_search { "query": { "bool" : { "must" : { "match" : { "file_path" : "16" } }, "filter": { "term" : { "file_path.tree" : "/User/alice" } } } } }