本地英文版地址: ../en/analysis-flatten-graph-tokenfilter.html
Flatten graph token filteredit
Flattens a token graph produced by a graph token filter, such
as synonym_graph or
word_delimiter_graph.
Flattening a token graph containing multi-position tokens makes the graph suitable for indexing. Otherwise, indexing does not support token graphs containing multi-position tokens.
Flattening graphs is a lossy process.
If possible, avoid using the flatten_graph filter. Instead, use graph token
filters in search analyzers only. This eliminates
the need for the flatten_graph filter.
The flatten_graph filter uses Lucene’s
FlattenGraphFilter.
Exampleedit
To see how the flatten_graph filter works, you first need to produce a token
graph containing multi-position tokens.
The following analyze API request uses the synonym_graph
filter to add dns as a multi-position synonym for domain name system in the
text domain name system is fragile:
GET /_analyze
{
"tokenizer": "standard",
"filter": [
{
"type": "synonym_graph",
"synonyms": [ "dns, domain name system" ]
}
],
"text": "domain name system is fragile"
}
The filter produces the following token graph with dns as a multi-position
token.
Indexing does not support token graphs containing multi-position tokens. To make this token graph suitable for indexing, it needs to be flattened.
To flatten the token graph, add the flatten_graph filter after the
synonym_graph filter in the previous analyze API request.
GET /_analyze
{
"tokenizer": "standard",
"filter": [
{
"type": "synonym_graph",
"synonyms": [ "dns, domain name system" ]
},
"flatten_graph"
],
"text": "domain name system is fragile"
}
The filter produces the following flattened token graph, which is suitable for indexing.
Add to an analyzeredit
The following create index API request uses the
flatten_graph token filter to configure a new
custom analyzer.
In this analyzer, a custom word_delimiter_graph filter produces token graphs
containing catenated, multi-position tokens. The flatten_graph filter flattens
these token graphs, making them suitable for indexing.
PUT /my_index
{
"settings": {
"analysis": {
"analyzer": {
"my_custom_index_analyzer": {
"type": "custom",
"tokenizer": "standard",
"filter": [
"my_custom_word_delimiter_graph_filter",
"flatten_graph"
]
}
},
"filter": {
"my_custom_word_delimiter_graph_filter": {
"type": "word_delimiter_graph",
"catenate_all": true
}
}
}
}
}