how to configure the synonyms_path in elasticsearch - search

Question

i'm pretty new to elasticsearch and i want to use synonyms, i added these lines in the configuration file:
index :
analysis :
analyzer :
synonym :
type : custom
tokenizer : whitespace
filter : [synonym]
filter :
synonym :
type : synonym
synonyms_path: synonyms.txt
then i created an index test:
"mappings" : {
"test" : {
"properties" : {
"text_1" : {
"type" : "string",
"analyzer" : "synonym"
},
"text_2" : {
"search_analyzer" : "standard",
"index_analyzer" : "synonym",
"type" : "string"
},
"text_3" : {
"type" : "string",
"analyzer" : "synonym"
}
}
}
}
and insrted a type test with this data:
{
"text_3" : "foo dog cat",
"text_2" : "foo dog cat",
"text_1" : "foo dog cat"
}
synonyms.txt contains "foo,bar,baz", and when i search for foo it returns what i expected but when i search for baz or bar it return zero results:
{
"query":{
"query_string":{
"query" : "bar",
"fields" : [ "text_1"],
"use_dis_max" : true,
"boost" : 1.0
}}}
result:
{
"took":1,
"timed_out":false,
"_shards":{
"total":5,
"successful":5,
"failed":0
},
"hits":{
"total":0,
"max_score":null,
"hits":[
]
}
}

Answer 1

I don't know, if your problem is because you defined bad the synonyms for "bar". As you said you are pretty new I'm going to put an example similar to yours that works. I want to show how elasticsearch deal with synonyms at search time and at index time. Hope it helps.
First thing create the synonym file:
foo => foo bar, baz
Now I create the index with the particular settings you are trying to test:
curl -XPUT 'http://localhost:9200/test/' -d '{
"settings": {
"index": {
"analysis": {
"analyzer": {
"synonym": {
"tokenizer": "whitespace",
"filter": ["synonym"]
}
},
"filter" : {
"synonym" : {
"type" : "synonym",
"synonyms_path" : "synonyms.txt"
}
}
}
}
},
"mappings": {
"test" : {
"properties" : {
"text_1" : {
"type" : "string",
"analyzer" : "synonym"
},
"text_2" : {
"search_analyzer" : "standard",
"index_analyzer" : "standard",
"type" : "string"
},
"text_3" : {
"type" : "string",
"search_analyzer" : "synonym",
"index_analyzer" : "standard"
}
}
}
}
}'
Note that synonyms.txt must be in the same directory that the configuration file since that path is relative to the config dir.
Now index a doc:
curl -XPUT 'http://localhost:9200/test/test/1' -d '{
"text_3": "baz dog cat",
"text_2": "foo dog cat",
"text_1": "foo dog cat"
}'
Now the searches
Searching in field text_1
curl -XGET 'http://localhost:9200/test/_search?q=text_1:baz'
{
"took": 3,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 1,
"max_score": 0.15342641,
"hits": [
{
"_index": "test",
"_type": "test",
"_id": "1",
"_score": 0.15342641,
"_source": {
"text_3": "baz dog cat",
"text_2": "foo dog cat",
"text_1": "foo dog cat"
}
}
]
}
}
You get the document because baz is synonym of foo and at index time foo is expanded with its synonyms
Searching in field text_2
curl -XGET 'http://localhost:9200/test/_search?q=text_2:baz'
result:
{
"took": 2,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 0,
"max_score": null,
"hits": []
}
}
I don't get hits because I didn't expand synonyms while indexing (standard analyzer). And, since I'm searching baz and baz is not in the text, I don't get any result.
Searching in field text_3
curl -XGET 'http://localhost:9200/test/_search?q=text_3:foo'
{
"took": 3,
"timed_out": false,
"_shards": {
"total": 5,
"successful": 5,
"failed": 0
},
"hits": {
"total": 1,
"max_score": 0.15342641,
"hits": [
{
"_index": "test",
"_type": "test",
"_id": "1",
"_score": 0.15342641,
"_source": {
"text_3": "baz dog cat",
"text_2": "foo dog cat",
"text_1": "foo dog cat"
}
}
]
}
}
Note: text_3 is "baz dog cat"
text_3 was indexes without expanding synonyms. As I'm searching for foo, which have "baz" as one of the synonyms I get the result.
If you want to debug you can use _analyze endpoint for example:
curl -XGET 'http://localhost:9200/test/_analyze?text=foo&analyzer=synonym&pretty=true'
result:
{
"tokens": [
{
"token": "foo",
"start_offset": 0,
"end_offset": 3,
"type": "SYNONYM",
"position": 1
},
{
"token": "baz",
"start_offset": 0,
"end_offset": 3,
"type": "SYNONYM",
"position": 1
},
{
"token": "bar",
"start_offset": 0,
"end_offset": 3,
"type": "SYNONYM",
"position": 2
}
]
}